diff --git a/packages/frontend-app-api/report.api.md b/packages/frontend-app-api/report.api.md
index 91a33d277d..d2a3ac4d3b 100644
--- a/packages/frontend-app-api/report.api.md
+++ b/packages/frontend-app-api/report.api.md
@@ -34,7 +34,9 @@ export function createSpecializedApp(options?: {
   extensionFactoryMiddleware?:
     | ExtensionFactoryMiddleware
     | ExtensionFactoryMiddleware[];
-  flags?: Record<string, boolean>;
+  flags?: {
+    allowUnknownExtensionConfig?: boolean;
+  };
 }): {
   apis: ApiHolder;
   tree: AppTree;
diff --git a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
index 3d356e2a74..dbe5868176 100644
--- a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
+++ b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
@@ -208,7 +208,7 @@ export function createSpecializedApp(options?: {
   extensionFactoryMiddleware?:
     | ExtensionFactoryMiddleware
     | ExtensionFactoryMiddleware[];
-  flags?: Record<string, boolean>;
+  flags?: { allowUnknownExtensionConfig?: boolean };
 }): { apis: ApiHolder; tree: AppTree } {
   const config = options?.config ?? new ConfigReader({}, 'empty-config');
   const features = deduplicateFeatures(options?.features ?? []);