diff --git a/csv_serialization.install b/csv_serialization.install
index f973e46..f5cb6b8 100644
--- a/csv_serialization.install
+++ b/csv_serialization.install
@@ -1,5 +1,11 @@
 <?php
 
+/**
+ * @file
+ */
+
+use Drupal\Component\Utility\DeprecationHelper;
+use Drupal\Core\Extension\Requirement\RequirementSeverity;
 use League\Csv\Writer;
 
 /**
@@ -19,7 +25,7 @@ function csv_serialization_requirements($phase) {
     if (!class_exists(Writer::class)) {
       $requirements['league_csv'] = [
         'description' => t('CSV Serialization requires the League\Csv library.'),
-        'severity' => REQUIREMENT_ERROR,
+        'severity' => DeprecationHelper::backwardsCompatibleCall(\Drupal::VERSION, '11.2.0', fn() => RequirementSeverity::Error, fn() => REQUIREMENT_ERROR),
       ];
     }
   }
diff --git a/tests/src/Functional/CsvRestExportTest.php b/tests/src/Functional/CsvRestExportTest.php
index b765faf..d4b03de 100644
--- a/tests/src/Functional/CsvRestExportTest.php
+++ b/tests/src/Functional/CsvRestExportTest.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests\csv_serialization\Functional;
 
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\Tests\views\Functional\ViewTestBase;
 
 /**
@@ -9,6 +11,8 @@ use Drupal\Tests\views\Functional\ViewTestBase;
  *
  * @group csv_serialization
  */
+#[Group('csv_serialization')]
+#[RunTestsInSeparateProcesses]
 class CsvRestExportTest extends ViewTestBase {
 
   /**
diff --git a/tests/src/Unit/CsvEncoderTest.php b/tests/src/Unit/CsvEncoderTest.php
index b78def6..ee535ce 100644
--- a/tests/src/Unit/CsvEncoderTest.php
+++ b/tests/src/Unit/CsvEncoderTest.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests\csv_serialization\Unit;
 
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\DataProvider;
 use Drupal\csv_serialization\Encoder\CsvEncoder;
 use Drupal\Tests\UnitTestCase;
 
@@ -10,6 +12,7 @@ use Drupal\Tests\UnitTestCase;
  *
  * @group test_example
  */
+#[Group('test_example')]
 class CsvEncoderTest extends UnitTestCase {
 
   /**
@@ -56,14 +59,14 @@ class CsvEncoderTest extends UnitTestCase {
         'title' => 'This is title 3',
         'body' => ['<p>This is, body 3</p>'],
         'images' => [
-        [
-          'src' => 'img1.jpg',
-          'alt' => 'Image 1',
-        ],
-        [
-          'src' => 'img2.jpg',
-          'alt' => 'Image, 2',
-        ],
+          [
+            'src' => 'img1.jpg',
+            'alt' => 'Image 1',
+          ],
+          [
+            'src' => 'img2.jpg',
+            'alt' => 'Image, 2',
+          ],
         ],
         'alias' => '',
         'status' => 0,
@@ -144,6 +147,7 @@ class CsvEncoderTest extends UnitTestCase {
    *
    * @dataProvider provideEncodeData
    */
+  #[DataProvider('provideEncodeData')]
   public function testEncodeCsv(array $csv_data, $csv_encoded_lf, $csv_encoded_crlf): void {
     // @todo Test passing in arguments to the constructor. E.g., $separator, $enclosure, strip_tags, etc.
     // Note that what we encode does not exactly represent the hierarchy of
@@ -179,6 +183,7 @@ class CsvEncoderTest extends UnitTestCase {
    *
    * @dataProvider provideDecodeData
    */
+  #[DataProvider('provideDecodeData')]
   public function testDecodeCsv(array $csv_encoded, $csv_data_lf, $csv_data_crlf) {
     $this->assertEquals($csv_encoded, $this->encoder->decode($csv_data_lf, 'csv'));
   }