this is my flutter code:

Future<void> permi() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var username = prefs.getString("username");
_fcm.getToken().then((value) => prefs.setString("fireToken", "$value!"));
print(_fcm.getToken());
var fireToken = prefs.getString("fireToken");
var token = prefs.getString("token");
await http
    .post(Uri.parse("http://192.168.0.111:3000/notiftoken"),
  headers:{"Content-Type": "application/json",
    "authorization": "$token"},
  body: jsonEncode({"username": username,"token": fireToken}),
)
    .then((value) => value)
    .catchError((e) => print(e));

 }

Future checkprm()async{
NotificationSettings settings =
await _fcm.requestPermission(
  alert: true,
  announcement: false,
  badge: true,
  carPlay: false,
  criticalAlert: false,
  provisional: false,
  sound: true,
);
NotificationSettings set = await _fcm.getNotificationSettings();
if (settings.authorizationStatus == AuthorizationStatus.authorized) {
  print('User granted permission');
} else if (settings.authorizationStatus == AuthorizationStatus.provisional) {
  print('User granted provisional permission');
} else {
  print('User declined or has not accepted permission');
}
}
@override
 void initState(){
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
  _fcm.getToken().then((value) => print("$value"));
  checkprm();
  permi();
  connect();
  super.initState();
  WidgetsBinding.instance.addObserver(this);
 }

this my node server :

admin.initializeApp({
 credential: admin.credential.cert(serviceAccount)
});

   async function sendNotif( title, body0,token){
    return await admin.messaging().sendMulticast({
    tokens: [token],
    notification: {
     title: title,
     body: body0
   },
   data: {
     title: "This is a firebase message",
     message: "expo-notifications should be triggered",
    "hello": "world",
     click_action: "FLUTTER_NOTIFICATION_CLICK"
  },
// Set Android priority to "high"
  android: {
   priority: "high",
   },
// Add APNS (Apple) config
  apns: {
   payload: {

     aps: {
       "contentAvailable": true,
      },
    },
    headers: {

      "apns-push-type": "background",
      "apns-priority": "5", // Must be `5` when `contentAvailable` is set to true.
      "apns-topic": "io.flutter.plugins.firebase.messaging", // bundle identifier

    },
  }
});

}
i’ve been searching for a solution for about two weeks but it’s all for nothing.
the issue is that i don’t receive notifications coming from firebase if anyone found a solution please tell us. .
.
.