Flutter FCM can't run onBackgroundMessage, can't save notifications locally when not clicked

I'm using flutter to make an android app and one of the features is to show and save push notifications from Firebase.

My question is How can I save the push notification when opening the app without clicking on the notification.

I implemented the fcm and I can get notifications when app is running (onMessage) / in background (onResume) / terminated (onLaunch),

I can save them locally to a repository using the above functions, however those are only called when user click on the notification, and not when the app is started using its icon.

I tried to save in onBackgroundMessage but it's never called, below is the testing function trying to print something when onBackgroundMessage, it is outside the App class:

Future<void> testing(Map<String, dynamic> message) {
  print("BACKGROUND MSG CALLED");
  return Future.value(null);
}

below is the code I run in the initState(),

ps. _showNotification will also call saveNotifcation() which works well.

firebaseMessaging.configure(
    onMessage: (Map<String, dynamic> msg) async {
    print("onMessage called $msg");
    await _showNotification(msg);
  },
   onBackgroundMessage:
       Platform.isAndroid ? testing : null,
  onLaunch: (Map<String, dynamic> msg) async {
    // give time for splashscreen to run and finish before it's done.
    SchedulerBinding.instance
        .addPostFrameCallback((_) => _showNotification(msg));
  },
  onResume: (Map<String, dynamic> msg) async {
    print("onResume called $msg");
    await _showNotification(msg);
  },
);
firebaseMessaging.requestNotificationPermissions(
    const IosNotificationSettings(
        sound: true, badge: true, alert: true, provisional: true));
firebaseMessaging.onIosSettingsRegistered
    .listen((IosNotificationSettings settings) {
  print("ios registered");
});
firebaseMessaging.getToken().then((){ print("printing Token: {$token}");});

I searched a lot but no solution could be found. any help will be much appreciated.

I'm using firebase_messaging: ^7.0.0

Flutter doctor -v:

    [✓] Flutter (Channel stable, 1.22.0, on Mac OS X 10.15.1 19B88, locale en)
    • Flutter version 1.22.0 at /Users/mine/flutter
    • Framework revision d408d302e2 (9 days ago), 2020-09-29 11:49:17 -0700
    • Engine revision 5babba6c4d
    • Dart version 2.10.0
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/mine/Library/Android/sdk
    • Platform android-29, build-tools 29.0.3
    • ANDROID_HOME = /Users/mine/Library/Android/sdk
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6222593)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.3.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.3.1, Build version 11C504
    • CocoaPods version 1.9.3

[✓] Android Studio (version 4.0)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 46.0.2
    • Dart plugin version 193.7361
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6222593)

[✓] VS Code (version 1.49.3)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.15.0

[✓] Connected device (1 available)
    • Mi 9T Pro (mobile) • 83b222f7 • android-arm64 • Android 10 (API 29)

• No issues found!