reverted:
--- b/core/modules/filter/filter.post_update.php
+++ /dev/null
@@ -1,39 +0,0 @@
-<?php
-
-/**
- * @file
- * Post update functions for Filter.
- */
-
-declare(strict_types=1);
-
-use Drupal\filter\Entity\FilterFormat;
-use Drupal\filter\FilterFormatInterface;
-use Drupal\filter\FilterPluginCollection;
-
-/**
- * Enable filter_image_lazy_load if editor_file_reference is enabled.
- */
-function filter_post_update_image_lazy_load(): void {
-  if (\Drupal::service('plugin.manager.filter')->hasDefinition('editor_file_reference')) {
-    foreach (FilterFormat::loadMultiple() as $format) {
-      \assert($format instanceof FilterFormatInterface);
-      $collection = $format->filters();
-      $configuration = $collection->getConfiguration();
-      \assert($collection instanceof FilterPluginCollection);
-      if (\array_key_exists('editor_file_reference', $configuration)) {
-        $collection->addInstanceId('filter_image_lazy_load');
-        $configuration['filter_image_lazy_load'] = [
-          'id' => 'filter_image_lazy_load',
-          'provider' => 'filter',
-          'status' => TRUE,
-          // Place lazy loading after editor file reference.
-          'weight' => $configuration['editor_file_reference']['weight'] + 1,
-          'settings' => [],
-        ];
-        $collection->setConfiguration($configuration);
-        $format->save();
-      }
-    }
-  }
-}
reverted:
--- b/core/modules/filter/src/Plugin/Filter/FilterImageLazyLoad.php
+++ /dev/null
@@ -1,124 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\filter\Plugin\Filter;
-
-use Drupal\Component\Utility\Html;
-use Drupal\Core\Entity\EntityRepositoryInterface;
-use Drupal\Core\Image\ImageFactory;
-use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
-use Drupal\file\FileInterface;
-use Drupal\filter\FilterProcessResult;
-use Drupal\filter\Plugin\FilterBase;
-use Symfony\Component\DependencyInjection\ContainerInterface;
-
-/**
- * Provides a filter to lazy load tracked images.
- *
- * @Filter(
- *   id = "filter_image_lazy_load",
- *   title = @Translation("Lazy load tracked images uploaded via a Text Editor"),
- *   description = @Translation("Instruct browsers to lazy load images, unless overridden by <code>&lt;img loading=&quot;eager&quot;&gt;</code>."),
- *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_REVERSIBLE,
- *   weight = 15
- * )
- */
-final class FilterImageLazyLoad extends FilterBase implements ContainerFactoryPluginInterface {
-
-  /**
-   * The entity repository.
-   *
-   * @var \Drupal\Core\Entity\EntityRepositoryInterface
-   */
-  protected $entityRepository;
-
-  /**
-   * The image factory.
-   *
-   * @var \Drupal\Core\Image\ImageFactory
-   */
-  protected $imageFactory;
-
-  /**
-   * Constructs a \Drupal\filter\Plugin\Filter\FilterImageLazyLoad object.
-   *
-   * @param array $configuration
-   *   A configuration array containing information about the plugin instance.
-   * @param string $plugin_id
-   *   The plugin_id for the plugin instance.
-   * @param mixed $plugin_definition
-   *   The plugin implementation definition.
-   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
-   *   The entity repository.
-   * @param \Drupal\Core\Image\ImageFactory $image_factory
-   *   The image factory.
-   */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityRepositoryInterface $entity_repository, ImageFactory $image_factory) {
-    $this->entityRepository = $entity_repository;
-    $this->imageFactory = $image_factory;
-    parent::__construct($configuration, $plugin_id, $plugin_definition);
-  }
-
-  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition): self {
-    return new self(
-      $configuration,
-      $plugin_id,
-      $plugin_definition,
-      $container->get('entity.repository'),
-      $container->get('image.factory')
-    );
-
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function process($text, $langcode): FilterProcessResult {
-    $result = new FilterProcessResult($text);
-
-    // If there are no images, exit early.
-    if (stripos($text, '<img ') === FALSE && stripos($text, 'data-entity-type="file"') === FALSE) {
-      return $result;
-    }
-
-    return $result->setProcessedText($this->transformImages($text));
-  }
-
-  /**
-   * Transform markup of images to include loading="lazy".
-   *
-   * @param string $text
-   *   The markup to transform.
-   *
-   * @return string
-   */
-  private function transformImages(string $text): string {
-    $dom = Html::load($text);
-    $xpath = new \DOMXPath($dom);
-    // Only set loading="lazy" if no existing loading attribute is specified.
-    foreach ($xpath->query('//img[not(@loading) and @data-entity-type="file" and @data-entity-uuid]') as $element) {
-      assert($element instanceof \DOMElement);
-      $uuid = $element->getAttribute('data-entity-uuid');
-      $file = $this->entityRepository->loadEntityByUuid('file', $uuid);
-      if ($file instanceof FileInterface) {
-        $image = $this->imageFactory->get($file->getFileUri());
-        $width = $image->getWidth();
-        $height = $image->getHeight();
-        // Set dimensions to avoid content layout shift (CLS).
-        if ($width !== NULL && !$element->hasAttribute('width')) {
-          $element->setAttribute('width', (string) $width);
-        }
-        if ($height !== NULL && !$element->hasAttribute('height')) {
-          $element->setAttribute('height', (string) $height);
-        }
-        // If dimensions are specified, then set lazy loading.
-        if ($element->hasAttribute('width') && $element->hasAttribute('height')) {
-          $element->setAttribute('loading', 'lazy');
-        }
-      }
-    }
-    return Html::serialize($dom);
-  }
-
-}
reverted:
--- b/core/modules/filter/tests/src/Functional/Update/FilterConfigTest.php
+++ /dev/null
@@ -1,48 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Drupal\Tests\filter\Functional\Update;
-
-use Drupal\FunctionalTests\Update\UpdatePathTestBase;
-
-/**
- * Tests updating filter module's configuration.
- *
- * @group Update
- */
-class FilterConfigTest extends UpdatePathTestBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  protected $defaultTheme = 'stark';
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setDatabaseDumpFiles(): void {
-    $this->databaseDumpFiles = [
-      __DIR__ . '/../../../../../system/tests/fixtures/update/drupal-8.8.0.bare.standard.php.gz',
-    ];
-  }
-
-  /**
-   * Tests upgrading filter settings.
-   *
-   * @see \filter_post_update_image_lazy_load()
-   */
-  public function testUpdateLazyImageLoad(): void {
-    $config = $this->config('filter.format.full_html');
-    $this->assertArrayNotHasKey('filter_image_lazy_load', $config->get('filters'));
-
-    // Run updates.
-    $this->runUpdates();
-
-    $config = $this->config('filter.format.full_html');
-    $filters = $config->get('filters');
-    $this->assertArrayHasKey('filter_image_lazy_load', $filters);
-    $this->assertEquals($filters['editor_file_reference']['weight'] + 1, $filters['filter_image_lazy_load']['weight']);
-  }
-
-}
reverted:
--- b/core/modules/filter/tests/src/Unit/FilterImageLazyLoadTest.php
+++ /dev/null
@@ -1,72 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\Tests\filter\Unit;
-
-use Drupal\Core\Entity\EntityRepositoryInterface;
-use Drupal\Core\Image\Image;
-use Drupal\Core\Image\ImageFactory;
-use Drupal\file\FileInterface;
-use Drupal\filter\Plugin\Filter\FilterImageLazyLoad;
-use Drupal\Tests\UnitTestCase;
-
-/**
- * @coversDefaultClass \Drupal\filter\Plugin\Filter\FilterImageLazyLoad
- * @group filter
- */
-final class FilterImageLazyLoadTest extends UnitTestCase {
-
-  /**
-   * @var \Drupal\filter\Plugin\Filter\FilterImageLazyLoad
-   */
-  protected $filter;
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp(): void {
-    $file = $this->prophesize(FileInterface::class);
-    $file->getFileUri()->willReturn('foo.png');
-    $entity_repository = $this->prophesize(EntityRepositoryInterface::class);
-    $entity_repository->loadEntityByUuid('file', 'a6d88b01-3b5e-4c02-bf26-24a0c48d61cd')->willReturn($file->reveal());
-    $image = $this->prophesize(Image::class);
-    $image->getHeight()->willReturn(100);
-    $image->getWidth()->willReturn(100);
-    $image_factory = $this->prophesize(ImageFactory::class);
-    $image_factory->get('foo.png')->willReturn($image->reveal());
-    $this->filter = new FilterImageLazyLoad([], 'filter_image_lazy_load', ['provider' => 'test'], $entity_repository->reveal(), $image_factory->reveal());
-    parent::setUp();
-  }
-
-  /**
-   * @covers ::process
-   *
-   * @dataProvider providerHtml
-   *
-   * @param string $html
-   *   Input HTML.
-   * @param string $expected
-   *   The expected output string.
-   */
-  public function testProcess(string $html, string $expected): void {
-    $this->assertSame($expected, $this->filter->process($html, 'en')->getProcessedText());
-  }
-
-  /**
-   * Provides data for testProcess.
-   *
-   * @return array
-   *   An array of test data.
-   */
-  public function providerHtml(): array {
-    return [
-      'lazy loading attribute already added' => ['<p><img src="foo.png" loading="lazy"></p>', '<p><img src="foo.png" loading="lazy" /></p>'],
-      'eager loading attribute already added' => ['<p><img src="foo.png" loading="eager"/></p>', '<p><img src="foo.png" loading="eager" /></p>'],
-      'no image tag' => ['<p>Lorem ipsum...</p>', '<p>Lorem ipsum...</p>'],
-      'no loading attribute nor uuid' => ['<p><img src="foo.png"></p>', '<p><img src="foo.png" /></p>'],
-      'no loading attribute but uuid' => ['<p><img src="foo.png" data-entity-type="file" data-entity-uuid="a6d88b01-3b5e-4c02-bf26-24a0c48d61cd"></p>', '<p><img src="foo.png" data-entity-type="file" data-entity-uuid="a6d88b01-3b5e-4c02-bf26-24a0c48d61cd" width="100" height="100" loading="lazy" /></p>'],
-    ];
-  }
-
-}
diff -u b/core/profiles/demo_umami/config/install/filter.format.basic_html.yml b/core/profiles/demo_umami/config/install/filter.format.basic_html.yml
--- b/core/profiles/demo_umami/config/install/filter.format.basic_html.yml
+++ b/core/profiles/demo_umami/config/install/filter.format.basic_html.yml
@@ -49,8 +49,8 @@
     status: true
     weight: 0
     settings: {  }
-  filter_image_lazy_load:
-    id: filter_image_lazy_load
+  editor_image_lazy_load:
+    id: editor_image_lazy_load
     provider: filter
     status: true
     weight: 10
diff -u b/core/profiles/standard/config/install/filter.format.basic_html.yml b/core/profiles/standard/config/install/filter.format.basic_html.yml
--- b/core/profiles/standard/config/install/filter.format.basic_html.yml
+++ b/core/profiles/standard/config/install/filter.format.basic_html.yml
@@ -36,8 +36,8 @@
     status: true
     weight: 9
     settings: {  }
-  filter_image_lazy_load:
-    id: filter_image_lazy_load
+  editor_image_lazy_load:
+    id: editor_image_lazy_load
     provider: filter
     status: true
     weight: 15
diff -u b/core/profiles/standard/config/install/filter.format.full_html.yml b/core/profiles/standard/config/install/filter.format.full_html.yml
--- b/core/profiles/standard/config/install/filter.format.full_html.yml
+++ b/core/profiles/standard/config/install/filter.format.full_html.yml
@@ -27,8 +27,8 @@
     status: true
     weight: 10
     settings: {  }
-  filter_image_lazy_load:
-    id: filter_image_lazy_load
+  editor_image_lazy_load:
+    id: editor_image_lazy_load
     provider: filter
     status: true
     weight: 15
only in patch2:
unchanged:
--- a/core/modules/editor/editor.module
+++ b/core/modules/editor/editor.module
@@ -182,6 +182,64 @@ function editor_form_filter_format_form_alter(&$form, FormStateInterface $form_s
   $form['actions']['submit']['#submit'][] = 'editor_form_filter_admin_format_submit';
 }
 
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function editor_form_filter_format_edit_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
+  // Add an additional validate callback so we can ensure the order of filters
+  // is correct.
+  $form['#validate'][] = 'editor_filter_format_edit_form_validate';
+}
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function editor_form_filter_format_add_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
+  // Add an additional validate callback so we can ensure the order of filters
+  // is correct.
+  $form['#validate'][] = 'editor_filter_format_edit_form_validate';
+}
+
+/**
+ * Validate callback to ensure filter order and allowed_html are compatible.
+ */
+function editor_filter_format_edit_form_validate($form, FormStateInterface $form_state) {
+  if ($form_state->getTriggeringElement()['#name'] !== 'op') {
+    return;
+  }
+
+  $lazy_load_enabled = $form_state->getValue([
+    'filters',
+    'editor_image_lazy_load',
+    'status',
+  ]);
+
+  if ($lazy_load_enabled !== 1) {
+    return;
+  }
+
+  $get_filter_label = function ($filter_plugin_id) use ($form) {
+    return (string) $form['filters']['order'][$filter_plugin_id]['filter']['#markup'];
+  };
+
+  $filters = $form_state->getValue('filters');
+
+  // The "editor_image_lazy_load" filter must run after "editor_file_reference".
+  $file_reference = $filters['editor_file_reference'];
+  $lazy_load = $filters['editor_image_lazy_load'];
+  if ($file_reference['weight'] >= $lazy_load['weight'] || $file_reference['status'] === 0) {
+    $error_message = new TranslatableMarkup(
+      'The %filter must be enabled and placed before the %lazy-load-filter-label filter.',
+      [
+        '%lazy-load-filter-label' => $get_filter_label('editor_image_lazy_load'),
+        '%filter' => $get_filter_label('editor_file_reference'),
+      ]
+    );
+
+    $form_state->setErrorByName('filters', $error_message);
+  }
+}
+
 /**
  * Button submit handler for filter_format_form()'s 'editor_configure' button.
  */
only in patch2:
unchanged:
--- a/core/modules/editor/editor.post_update.php
+++ b/core/modules/editor/editor.post_update.php
@@ -5,6 +5,10 @@
  * Post update functions for Editor.
  */
 
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\filter\FilterFormatInterface;
+use Drupal\filter\FilterPluginCollection;
+
 /**
  * Implements hook_removed_post_updates().
  */
@@ -13,3 +17,30 @@ function editor_removed_post_updates() {
     'editor_post_update_clear_cache_for_file_reference_filter' => '9.0.0',
   ];
 }
+
+/**
+ * Enable filter_image_lazy_load if editor_file_reference is enabled.
+ */
+function editor_post_update_image_lazy_load(): void {
+  if (\Drupal::service('plugin.manager.filter')->hasDefinition('editor_file_reference')) {
+    foreach (FilterFormat::loadMultiple() as $format) {
+      \assert($format instanceof FilterFormatInterface);
+      $collection = $format->filters();
+      $configuration = $collection->getConfiguration();
+      \assert($collection instanceof FilterPluginCollection);
+      if (array_key_exists('editor_file_reference', $configuration)) {
+        $collection->addInstanceId('editor_image_lazy_load');
+        $configuration['editor_image_lazy_load'] = [
+          'id' => 'editor_image_lazy_load',
+          'provider' => 'filter',
+          'status' => TRUE,
+          // Place lazy loading after editor file reference.
+          'weight' => $configuration['editor_file_reference']['weight'] + 1,
+          'settings' => [],
+        ];
+        $collection->setConfiguration($configuration);
+        $format->save();
+      }
+    }
+  }
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/editor/src/Plugin/Filter/EditorImageLazyLoad.php
@@ -0,0 +1,127 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\editor\Plugin\Filter;
+
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Entity\EntityRepositoryInterface;
+use Drupal\Core\Image\ImageFactory;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\file\FileInterface;
+use Drupal\filter\FilterProcessResult;
+use Drupal\filter\Plugin\FilterBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a filter to lazy load tracked images.
+ *
+ * @Filter(
+ *   id = "editor_image_lazy_load",
+ *   title = @Translation("Lazy load tracked images uploaded via a Text Editor"),
+ *   description = @Translation("Instruct browsers to lazy load images, unless overridden by <code>&lt;img loading=&quot;eager&quot;&gt;</code>."),
+ *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_REVERSIBLE,
+ *   weight = 15
+ * )
+ */
+final class EditorImageLazyLoad extends FilterBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The entity repository.
+   *
+   * @var \Drupal\Core\Entity\EntityRepositoryInterface
+   */
+  protected $entityRepository;
+
+  /**
+   * The image factory.
+   *
+   * @var \Drupal\Core\Image\ImageFactory
+   */
+  protected $imageFactory;
+
+  /**
+   * Constructs a FilterImageLazyLoad object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
+   *   The entity repository.
+   * @param \Drupal\Core\Image\ImageFactory $image_factory
+   *   The image factory.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityRepositoryInterface $entity_repository, ImageFactory $image_factory) {
+    $this->entityRepository = $entity_repository;
+    $this->imageFactory = $image_factory;
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition): self {
+    return new self(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('entity.repository'),
+      $container->get('image.factory')
+    );
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function process($text, $langcode): FilterProcessResult {
+    $result = new FilterProcessResult($text);
+
+    // If there are no images, exit early.
+    if (stripos($text, '<img ') === FALSE && stripos($text, 'data-entity-type="file"') === FALSE) {
+      return $result;
+    }
+
+    return $result->setProcessedText($this->transformImages($text));
+  }
+
+  /**
+   * Transform markup of images to include loading="lazy".
+   *
+   * @param string $text
+   *   The markup to transform.
+   *
+   * @return string
+   */
+  private function transformImages(string $text): string {
+    $dom = Html::load($text);
+    $xpath = new \DOMXPath($dom);
+    // Only set loading="lazy" if no existing loading attribute is specified.
+    foreach ($xpath->query('//img[not(@loading) and @data-entity-type="file" and @data-entity-uuid]') as $element) {
+      assert($element instanceof \DOMElement);
+      $uuid = $element->getAttribute('data-entity-uuid');
+      $file = $this->entityRepository->loadEntityByUuid('file', $uuid);
+      if ($file instanceof FileInterface) {
+        $image = $this->imageFactory->get($file->getFileUri());
+        $width = $image->getWidth();
+        $height = $image->getHeight();
+        // Set dimensions to avoid content layout shift (CLS).
+        if ($width !== NULL && !$element->hasAttribute('width')) {
+          $element->setAttribute('width', (string) $width);
+        }
+        if ($height !== NULL && !$element->hasAttribute('height')) {
+          $element->setAttribute('height', (string) $height);
+        }
+        // If dimensions are specified, then set lazy loading.
+        if ($element->hasAttribute('width') && $element->hasAttribute('height')) {
+          $element->setAttribute('loading', 'lazy');
+        }
+      }
+    }
+    return Html::serialize($dom);
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/editor/tests/src/Functional/Update/EditorFilterConfigTest.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\editor\Functional\Update;
+
+use Drupal\FunctionalTests\Update\UpdatePathTestBase;
+
+/**
+ * Tests updating editor module's configuration.
+ *
+ * @group Update
+ */
+class EditorFilterConfigTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setDatabaseDumpFiles(): void {
+    $this->databaseDumpFiles = [
+      __DIR__ . '/../../../../../system/tests/fixtures/update/drupal-8.8.0.bare.standard.php.gz',
+    ];
+  }
+
+  /**
+   * Tests upgrading filter settings.
+   *
+   * @see filter_post_update_image_lazy_load()
+   */
+  public function testUpdateLazyImageLoad(): void {
+    $config = $this->config('filter.format.full_html');
+    $this->assertArrayNotHasKey('editor_image_lazy_load', $config->get('filters'));
+
+    $this->runUpdates();
+
+    $config = $this->config('filter.format.full_html');
+    $filters = $config->get('filters');
+    $this->assertArrayHasKey('editor_image_lazy_load', $filters);
+    $this->assertEquals($filters['editor_file_reference']['weight'] + 1, $filters['editor_image_lazy_load']['weight']);
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/editor/tests/src/Unit/EditorImageLazyLoadTest.php
@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\Tests\editor\Unit;
+
+use Drupal\Core\Entity\EntityRepositoryInterface;
+use Drupal\Core\Image\Image;
+use Drupal\Core\Image\ImageFactory;
+use Drupal\file\FileInterface;
+use Drupal\filter\Plugin\Filter\EditorImageLazyLoad;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\editor\Plugin\Filter\EditorImageLazyLoad
+ * @group filter
+ */
+final class EditorImageLazyLoadTest extends UnitTestCase {
+
+  /**
+   * @var \Drupal\filter\Plugin\Filter\EditorImageLazyLoad
+   */
+  protected $filter;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    $file = $this->prophesize(FileInterface::class);
+    $file->getFileUri()->willReturn('foo.png');
+    $entity_repository = $this->prophesize(EntityRepositoryInterface::class);
+    $entity_repository->loadEntityByUuid('file', 'a6d88b01-3b5e-4c02-bf26-24a0c48d61cd')->willReturn($file->reveal());
+    $image = $this->prophesize(Image::class);
+    $image->getHeight()->willReturn(100);
+    $image->getWidth()->willReturn(100);
+    $image_factory = $this->prophesize(ImageFactory::class);
+    $image_factory->get('foo.png')->willReturn($image->reveal());
+    $this->filter = new EditorImageLazyLoad([], 'editor_image_lazy_load', ['provider' => 'test'], $entity_repository->reveal(), $image_factory->reveal());
+    parent::setUp();
+  }
+
+  /**
+   * @covers ::process
+   *
+   * @dataProvider providerHtml
+   *
+   * @param string $html
+   *   Input HTML.
+   * @param string $expected
+   *   The expected output string.
+   */
+  public function testProcess(string $html, string $expected): void {
+    $this->assertSame($expected, $this->filter->process($html, 'en')->getProcessedText());
+  }
+
+  /**
+   * Provides data for testProcess.
+   *
+   * @return array
+   *   An array of test data.
+   */
+  public function providerHtml(): array {
+    return [
+      'lazy loading attribute already added' => ['<p><img src="foo.png" loading="lazy"></p>', '<p><img src="foo.png" loading="lazy" /></p>'],
+      'eager loading attribute already added' => ['<p><img src="foo.png" loading="eager"/></p>', '<p><img src="foo.png" loading="eager" /></p>'],
+      'no image tag' => ['<p>Lorem ipsum...</p>', '<p>Lorem ipsum...</p>'],
+      'no loading attribute nor uuid' => ['<p><img src="foo.png"></p>', '<p><img src="foo.png" /></p>'],
+      'no loading attribute but uuid' => ['<p><img src="foo.png" data-entity-type="file" data-entity-uuid="a6d88b01-3b5e-4c02-bf26-24a0c48d61cd"></p>', '<p><img src="foo.png" data-entity-type="file" data-entity-uuid="a6d88b01-3b5e-4c02-bf26-24a0c48d61cd" width="100" height="100" loading="lazy" /></p>'],
+    ];
+  }
+
+}