Issue #3309585 by Mingsong, Wim Leers, Chi: CKEditor 5 Style plugin...

Issue #3309585 by Mingsong, Wim Leers, Chi: CKEditor 5 Style plugin configuration tab does not appear

(cherry picked from commit fc024f35)

core/modules/ckeditor5/src/Plugin/Editor/CKEditor5.php

@@ -687,7 +687,7 @@ public function validateConfigurationForm(array &$form, FormStateInterface $form
 
       // Special case: AJAX updates that do not submit the form (that cannot
       // result in configuration being saved).
-      if ($form_state->getSubmitHandlers() === ['editor_form_filter_admin_format_editor_configure']) {
+      if (in_array('editor_form_filter_admin_format_editor_configure', $form_state->getSubmitHandlers(), TRUE)) {
         // Ensure that plugins' validation constraints do not immediately
         // trigger a validation error: the user may choose to configure other
         // CKEditor 5 aspects first.