Issue #3024386: Deprecate NodePreviewController::title

core/modules/node/node.routing.yml

@@ -42,7 +42,6 @@ entity.node.preview:
   path: '/node/preview/{node_preview}/{view_mode_id}'
   defaults:
     _controller: '\Drupal\node\Controller\NodePreviewController::view'
-    _title_callback: '\Drupal\node\Controller\NodePreviewController::title'
   requirements:
     _node_preview_access: '{node_preview}'
   options:

core/modules/node/src/Controller/NodePreviewController.php

@@ -70,8 +70,13 @@ public function view(EntityInterface $node_preview, $view_mode_id = 'full', $lan
    *
    * @return string
    *   The page title.
+   *
+   * @deprecated in drupal:11.2.0 and is removed from drupal:12.0.0. There is no
+   * replacement.
+   * @see https://www.drupal.org/node/3518065
    */
   public function title(EntityInterface $node_preview) {
+    @trigger_error(__METHOD__ . ' is deprecated in drupal:11.2.0 and is removed from drupal:12.0.0. There is no replacement. See https://www.drupal.org/node/3518065', E_USER_DEPRECATED);
     return $this->entityRepository->getTranslationFromContext($node_preview)->label();
   }