diff --git a/core/lib/Drupal/Core/Entity/EntityHandlerBase.php b/core/lib/Drupal/Core/Entity/EntityHandlerBase.php
index c325542..e1a1268 100644
--- a/core/lib/Drupal/Core/Entity/EntityHandlerBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityHandlerBase.php
@@ -14,6 +14,7 @@
 /**
  * Provides a base class for entity handlers.
  *
+ * @deprecated for 9.x.
  * @todo Deprecate this in https://www.drupal.org/node/2471663.
  */
 abstract class EntityHandlerBase {