diff -u b/core/modules/comment/src/CommentViewBuilder.php b/core/modules/comment/src/CommentViewBuilder.php
--- b/core/modules/comment/src/CommentViewBuilder.php
+++ b/core/modules/comment/src/CommentViewBuilder.php
@@ -82,7 +82,7 @@
     // Store a threading field setting to use later in self::buildComponents().
     $commented_entity = $entity->getCommentedEntity();
     $build['#comment_threaded'] =
-      !$commented_entity
+      is_null($commented_entity)
       || $commented_entity->getFieldDefinition($entity->getFieldName())
         ->getSetting('default_mode') === CommentManagerInterface::COMMENT_MODE_THREADED;
     // If threading is enabled, don't render cache individual comments, but do
@@ -144,7 +144,7 @@
       $commented_entity = $entity->getCommentedEntity();
       // Set defaults if the commented_entity does not exist.
       $bundle = $commented_entity ? $commented_entity->bundle() : '';
-      $entity_type_id = $commented_entity ? $commented_entity->getEntityTypeId() === 'node' : NULL;
+      $is_node = $commented_entity ? $commented_entity->getEntityTypeId() === 'node' : NULL;
 
       $build[$id]['#entity'] = $entity;
       $build[$id]['#theme'] = 'comment__' . $entity->getFieldName() . '__' . $bundle;
@@ -168,7 +168,7 @@
         $build[$id]['#attached'] = [];
       }
       $build[$id]['#attached']['library'][] = 'comment/drupal.comment-by-viewer';
-      if ($attach_history && $entity_type_id) {
+      if ($attach_history && $is_node) {
         $build[$id]['#attached']['library'][] = 'comment/drupal.comment-new-indicator';
 
         // Embed the metadata for the comment "new" indicators on this node.
diff -u b/core/modules/comment/tests/src/Functional/CommentOrphanedTest.php b/core/modules/comment/tests/src/Functional/CommentOrphanedTest.php
--- b/core/modules/comment/tests/src/Functional/CommentOrphanedTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentOrphanedTest.php
@@ -51,7 +51,7 @@
     $ids = [1, 2];
     $entities = $comment_storage->loadMultiple($ids);
     foreach ($entities as $entity) {
-      $built = $this->buildEntityView($entity, 'full', NULL, TRUE);
+      $built = $this->buildEntityView($entity, 'full', NULL);
       $renderer->renderPlain($built);
     }
 
@@ -72,7 +72,7 @@
     $ids = [1, 2];
     $entities = $comment_storage->loadMultiple($ids);
     foreach ($entities as $entity) {
-      $built = $this->buildEntityView($entity, 'full', NULL, TRUE);
+      $built = $this->buildEntityView($entity, 'full', NULL);
       $renderer->renderPlain($built);
     }
 
reverted:
--- b/core/tests/Drupal/Tests/EntityViewTrait.php
+++ a/core/tests/Drupal/Tests/EntityViewTrait.php
@@ -61,7 +61,7 @@
 
     $render_controller = $this->container->get('entity_type.manager')->getViewBuilder($entity->getEntityTypeId());
     if ($reset) {
+      $render_controller->resetCache([$entity->id()]);
-      $render_controller->resetCache([$entity]);
     }
     $build = $render_controller->view($entity, $view_mode, $langcode);
     $ensure_fully_built($build);