diff -u b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
--- b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
+++ b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
@@ -219,8 +219,7 @@
     $fields['entity_id'] = FieldDefinition::create('entity_reference')
       ->setLabel(t('Entity ID'))
       ->setDescription(t('The ID of the entity of which this comment is a reply.'))
-      ->setRequired(TRUE)
-      ->setSetting('target_type', 'comment');
+      ->setRequired(TRUE);
 
     $fields['langcode'] = FieldDefinition::create('language')
       ->setLabel(t('Language code'))