Issue #3263668 by omkar-pd, Wim Leers, hooroomoo: Re-enable inline form errors...

    $form_state->set('ckeditor5_is_active', $already_using_ckeditor5);

    $form_state->set('ckeditor5_is_selected', $form_state->getValue(['editor', 'editor']) === 'ckeditor5');

    // Disable inline form errors when using CKEditor 5 because it prevents

    // useful error messages from vertical tabs from being visible to the user.

    // @todo Remove this workaround in

    //   https://www.drupal.org/project/drupal/issues/3263668

    if ($form_state->get('ckeditor5_is_selected')) {

      $element['#disable_inline_form_errors'] = TRUE;

    }

    return $element;

  }