Firebase messaging not working [Not receiving notfications] but app connected to Firebase

I was following a tutorial for firebase push notifications, I followed all the steps: Connecting the app to firebase, importing packages (Firebase messaging and Firebase push notifications), I tried sending several notifications but it did not work.

I know my app is connected to firebase as I am receiving data from cloud firestore and authentication also works and I am also able to write data to storage :

My main.dart:

void main() async {
  await Firebase.initializeApp(
    // Added actual values
    options: const FirebaseOptions(
      apiKey: "have added this ",
      appId: "have added this",
      messagingSenderId: "have added this",
      projectId: "have added this",
      storageBucket: "have added this",
  runApp(const MyApp());

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  State<MyApp> createState() => _MyAppState();

class _MyAppState extends State<MyApp> {
  void initState() {

        .getInitialMessage(); /this helps code below work great

    FirebaseMessaging.onMessage.listen((message) {
      if (message.notification != null) {
    FirebaseMessaging.onMessageOpenedApp.listen((message) {
      final routeFromMessage =['route'];


  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (context) => GoogleSignInProvider(),
      child: OverlaySupport(
        child: MaterialApp(
            title: 'News_App_admin',
            theme: ThemeData(
              buttonTheme: const ButtonThemeData(minWidth: 80),
              secondaryHeaderColor: const Color.fromARGB(255, 75, 177, 78),
            home: // MyHomePage(title: 'Home page'),
              builder: (ctx, userSnapshot) {
                if (userSnapshot.hasError) {
                    child: Text('Unknown Error'),
                if (userSnapshot.hasData) {
                  return bottomNavigationBar();
                return const Auth_Screen();
              stream: FirebaseAuth.instance.authStateChanges(),