diff -u b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
--- b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
+++ b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
@@ -20,7 +20,12 @@
    */
   const FIELD_UI_PREFIX = 'admin/structure/types/manage/bundle_for_testing_fields';
 
-  public static $modules = [
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = [
     'layout_builder',
     'block',
     'node',