diff --git a/src/Routing/Routes.php b/src/Routing/Routes.php
index eeba4f0..a6860f0 100644
--- a/src/Routing/Routes.php
+++ b/src/Routing/Routes.php
@@ -239,7 +239,6 @@ class Routes implements ContainerInjectionInterface {
         ? ['GET', 'POST', 'PATCH', 'DELETE']
         : ['GET']
       );
-      // @todo: remove the _on_relationship default in https://www.drupal.org/project/jsonapi/issues/2953346.
       $relationship_route->addDefaults(['_on_relationship' => TRUE]);
       $relationship_route->addDefaults(['serialization_class' => Relationship::class]);
       $relationship_route->addDefaults(['related' => $relationship_field_name]);