diff --git a/core/modules/layout_builder/src/Routing/LayoutBuilderRoutes.php b/core/modules/layout_builder/src/Routing/LayoutBuilderRoutes.php
index 735538ccf7..500a380a11 100644
--- a/core/modules/layout_builder/src/Routing/LayoutBuilderRoutes.php
+++ b/core/modules/layout_builder/src/Routing/LayoutBuilderRoutes.php
@@ -109,9 +109,10 @@ public function onAlterRoutes(RouteBuildEvent $event) {
         $requirements['_field_ui_view_mode_access'] = 'administer ' . $entity_type_id . ' display';
 
         $options['parameters']['section_storage']['layout_builder_tempstore'] = TRUE;
-        $options['_admin_route'] = FALSE;
         // Merge the entity route options in after Layout Builder's.
         $options = NestedArray::mergeDeep($options, $entity_route->getOptions());
+        // Disable the admin route flag after merging in entity route options.
+        $options['_admin_route'] = FALSE;
 
         $routes = $this->buildRoute(LayoutBuilderEntityViewDisplay::class, 'entity.entity_view_display.' . $entity_type_id, $path, $defaults, $requirements, $options);
         foreach ($routes as $name => $route) {
diff --git a/core/modules/layout_builder/tests/src/Unit/LayoutBuilderRoutesTest.php b/core/modules/layout_builder/tests/src/Unit/LayoutBuilderRoutesTest.php
index 08e234eaa2..961b870429 100644
--- a/core/modules/layout_builder/tests/src/Unit/LayoutBuilderRoutesTest.php
+++ b/core/modules/layout_builder/tests/src/Unit/LayoutBuilderRoutesTest.php
@@ -508,12 +508,12 @@ public function testGetRoutes() {
    */
   public function testOnAlterRoutes() {
     $collection = new RouteCollection();
-    $collection->add('known', new Route('/admin/entity/whatever'));
+    $collection->add('known', new Route('/admin/entity/whatever', [], [], ['_admin_route' => TRUE]));
     $collection->add('with_bundle', new Route('/admin/entity/{bundle}'));
     $event = new RouteBuildEvent($collection);
 
     $expected = [
-      'known' => new Route('/admin/entity/whatever'),
+      'known' => new Route('/admin/entity/whatever', [], [], ['_admin_route' => TRUE]),
       'with_bundle' => new Route('/admin/entity/{bundle}'),
       'entity.entity_view_display.with_field_ui_route.layout_builder' => new Route(
         '/admin/entity/whatever/display-layout/{view_mode_name}',