diff -u b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
--- b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -388,9 +388,11 @@
     // 200 for well-formed HEAD request.
     $response = $this->request('HEAD', $url, $request_options);
     $this->assertResourceResponse(200, '', $response);
-    // @todo Remove the if-test, remove the 'else', keep the body of the 'if' once https://www.drupal.org/node/2874938 lands.
-    // Dynamic Page Cache does not work for admin routes.
-    // @see \Drupal\dynamic_page_cache\PageCache\ResponsePolicy\DenyAdminRoutes
+    // @todo Entity resources with URLs that begin with '/admin/' are marked as
+    //   administrative (see https://www.drupal.org/node/2874938), which
+    //   excludes them from Dynamic Page Cache (see
+    //   https://www.drupal.org/node/2877528). When either of those issues is
+    //   fixed, remove the if-test and the 'else' block.
     if (strpos($this->entity->getEntityType()->getLinkTemplate('canonical'), '/admin/') !== 0) {
       $this->assertTrue($response->hasHeader('X-Drupal-Dynamic-Cache'));
       $this->assertSame(['MISS'], $response->getHeader('X-Drupal-Dynamic-Cache'));
@@ -410,9 +412,11 @@
     // Same for Dynamic Page Cache hit.
     $response = $this->request('GET', $url, $request_options);
     $this->assertResourceResponse(200, FALSE, $response);
-    // @todo Remove the if-test, remove the 'else', keep the body of the 'if' once https://www.drupal.org/node/2874938 lands.
-    // Dynamic Page Cache does not work for admin routes.
-    // @see \Drupal\dynamic_page_cache\PageCache\ResponsePolicy\DenyAdminRoutes
+    // @todo Entity resources with URLs that begin with '/admin/' are marked as
+    //   administrative (see https://www.drupal.org/node/2874938), which
+    //   excludes them from Dynamic Page Cache (see
+    //   https://www.drupal.org/node/2877528). When either of those issues is
+    //   fixed, remove the if-test and the 'else' block.
     if (strpos($this->entity->getEntityType()->getLinkTemplate('canonical'), '/admin/') !== 0) {
       $this->assertTrue($response->hasHeader('X-Drupal-Dynamic-Cache'));
       if (!static::$auth) {