diff -u b/core/lib/Drupal/Core/Render/Renderer.php b/core/lib/Drupal/Core/Render/Renderer.php
--- b/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -506,12 +506,7 @@
         $elements['#children'] = call_user_func($callable, $elements['#children'], $elements);
       }
     }
-
-    // When render elements are being rendered, the caller is responsible of
-    // wrapping the render element with prefix and suffix to ensure that they
-    // are added only once, and that they are added in the final start and
-    // ending.
-
+    
     // Only apply the prefix and suffix markup around the children if they have
     // not already been rendered by the theme manager.
     if (!isset($elements['#render_children'])) {