diff --git a/libraries/src/Extension/PluginInterface.php b/libraries/src/Extension/PluginInterface.php
index 9ac414a7d869c..5c56d9d73c0e5 100644
--- a/libraries/src/Extension/PluginInterface.php
+++ b/libraries/src/Extension/PluginInterface.php
@@ -30,6 +30,10 @@ interface PluginInterface extends DispatcherAwareInterface
      * @return  void
      *
      * @since   4.0.0
+     *
+     * @deprecated  __DEPLOY_VERSION__ will be removed in 7.0
+     *              Plugin should implement SubscriberInterface.
+     *              These plugins will be added to dispatcher in PluginHelper::import().
      */
     public function registerListeners();
 }
diff --git a/libraries/src/Plugin/CMSPlugin.php b/libraries/src/Plugin/CMSPlugin.php
index 37a93a302106d..61475104b4f30 100644
--- a/libraries/src/Plugin/CMSPlugin.php
+++ b/libraries/src/Plugin/CMSPlugin.php
@@ -222,6 +222,10 @@ public function loadLanguage($extension = '', $basePath = JPATH_ADMINISTRATOR)
      * @return  void
      *
      * @since   4.0.0
+     *
+     * @deprecated  __DEPLOY_VERSION__ will be removed in 7.0
+     *              Plugin should implement SubscriberInterface.
+     *              These plugins will be added to dispatcher in PluginHelper::import().
      */
     public function registerListeners()
     {
@@ -232,6 +236,8 @@ public function registerListeners()
             return;
         }
 
+        @trigger_error('The plugin should implement SubscriberInterface.', \E_USER_DEPRECATED);
+
         $reflectedObject = new \ReflectionObject($this);
         $methods         = $reflectedObject->getMethods(\ReflectionMethod::IS_PUBLIC);
 
@@ -287,6 +293,9 @@ public function registerListeners()
      * @return  void
      *
      * @since   4.0.0
+     *
+     * @deprecated  __DEPLOY_VERSION__ will be removed in 7.0
+     *              Plugin should implement SubscriberInterface.
      */
     final protected function registerLegacyListener(string $methodName)
     {
@@ -335,6 +344,9 @@ function (AbstractEvent $event) use ($methodName) {
      * @return  void
      *
      * @since   4.0.0
+     *
+     * @deprecated  __DEPLOY_VERSION__ will be removed in 7.0
+     *              Plugin should implement SubscriberInterface.
      */
     final protected function registerListener(string $methodName)
     {
@@ -349,6 +361,9 @@ final protected function registerListener(string $methodName)
      * @return  boolean
      *
      * @since   4.0.0
+     *
+     * @deprecated  __DEPLOY_VERSION__ will be removed in 7.0
+     *              Plugin should implement SubscriberInterface.
      */
     private function parameterImplementsEventInterface(\ReflectionParameter $parameter): bool
     {
diff --git a/libraries/src/Plugin/PluginHelper.php b/libraries/src/Plugin/PluginHelper.php
index b2681071f3282..08ac384b26d83 100644
--- a/libraries/src/Plugin/PluginHelper.php
+++ b/libraries/src/Plugin/PluginHelper.php
@@ -239,6 +239,7 @@ protected static function import($plugin, $autocreate = true, ?DispatcherInterfa
             return;
         }
 
+        // @TODO: Starting from 7.0 it should use $dispatcher->addSubscriber($plugin); for plugins which implement SubscriberInterface.
         $plugin->registerListeners();
     }