diff --git a/core/modules/filter/src/Plugin/Filter/FilterHtml.php b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
index c4ccc1d..2997afc 100644
--- a/core/modules/filter/src/Plugin/Filter/FilterHtml.php
+++ b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
@@ -21,7 +21,7 @@
  *   title = @Translation("Limit allowed HTML tags and correct faulty HTML"),
  *   type = Drupal\filter\Plugin\FilterInterface::TYPE_HTML_RESTRICTOR,
  *   settings = {
- *     "allowed_html" = TRUE,
+ *     "allowed_html" = "<a href hreflang> <em> <strong> <cite> <blockquote cite> <code> <ul type> <ol start type='1 A I'> <li> <dl> <dt> <dd> <h2 id='jump-*'> <h3 id> <h4 id> <h5 id> <h6 id>",
  *     "filter_html_help" = TRUE,
  *     "filter_html_nofollow" = FALSE
  *   },
@@ -88,13 +88,15 @@ public function preRenderAllowedHtml($element) {
    * {@inheritdoc}
    */
   public function setConfiguration(array $configuration) {
-    // The allowed_html setting is stored as an array of elements and
-    // attributes. The default annotation configuration for a plugin is merged
-    // into the actual configuration. So that we can support a default
-    // configuration that isn't merged and thus certain elements forced to be
-    // enabled, only set the configuration when allowed_html is TRUE as
-    // specified in the annotation.
-    if (!isset($configuration['settings']['allowed_html']) || $configuration['settings']['allowed_html'] === TRUE) {
+    // The allowed_html setting is stored as a sequence of elements and
+    // attributes. The default configuration in the plugin annotation
+    // is deep merged into the actual configuration in FilterPluginCollection.
+    // So that we aren't deep merging the default configuration with the actual
+    // configuration of a plugin (thus making it impossible to remove an element
+    // in the list of defaults), we specify the default in the string
+    // representation and convert it to the stored array representation.
+    // @see \Drupal\filter\FilterPluginCollection::initializePlugin()
+    if (!isset($configuration['settings']['allowed_html']) || is_string($configuration['settings']['allowed_html'])) {
       $configuration['settings']['allowed_html'] = $this->defaultConfiguration()['settings']['allowed_html'];
     }
     parent::setConfiguration($configuration);
@@ -107,45 +109,12 @@ public function setConfiguration(array $configuration) {
    */
   public function defaultConfiguration() {
     $default_configuration = parent::defaultConfiguration();
-    $default_configuration['settings']['allowed_html'] = [
-      'a' => [
-        'href' => '*',
-        'hreflang' => '*',
-      ],
-      'em' => [],
-      'strong' => [],
-      'cite' => [],
-      'blockquote' => [
-        'cite' => '*',
-      ],
-      'code' => [],
-      'ul' => [
-        'type' => '*',
-      ],
-      'ol' => [
-        'start' => '*',
-        'type' => '1 A I',
-      ],
-      'li' => [],
-      'dl' => [],
-      'dt' => [],
-      'dd' => [],
-      'h2' => [
-        'id' => 'jump-*',
-      ],
-      'h3' => [
-        'id' => '*',
-      ],
-      'h4' => [
-        'id' => '*',
-      ],
-      'h5' => [
-        'id' => '*',
-      ],
-      'h6' => [
-        'id' => '*',
-      ],
-    ];
+    // Convert the string representation of the allowed_html setting to an
+    // array.
+    // @see ::setConfiguration()
+    if (is_string($default_configuration['settings']['allowed_html'])) {
+      $default_configuration['settings']['allowed_html'] = static::convertAllowedHtmlStringToArray($default_configuration['settings']['allowed_html']);
+    }
     return $default_configuration;
   }
 
diff --git a/core/modules/filter/tests/src/Kernel/Plugin/migrate/process/FilterSettingsTest.php b/core/modules/filter/tests/src/Kernel/Plugin/migrate/process/FilterSettingsTest.php
index 4250211..e34c7ce 100644
--- a/core/modules/filter/tests/src/Kernel/Plugin/migrate/process/FilterSettingsTest.php
+++ b/core/modules/filter/tests/src/Kernel/Plugin/migrate/process/FilterSettingsTest.php
@@ -93,7 +93,27 @@ public function dataProvider() {
         ],
         'filter_html',
         [
-          'allowed_html' => '<a href hreflang> <em> <strong> <cite> <code> <ul type> <ol start type> <li> <dl> <dt> <dd>',
+          'allowed_html' => [
+            'a' => [
+              'href' => '*',
+              'hreflang' => '*',
+            ],
+            'em' => [],
+            'strong' => [],
+            'cite' => [],
+            'code' => [],
+            'ul' => [
+              'type' => '*',
+            ],
+            'ol' => [
+              'start' => '*',
+              'type' => '*',
+            ],
+            'li' => [],
+            'dl' => [],
+            'dt' => [],
+            'dd' => [],
+          ],
         ],
       ],
     ];