Flutter push notification's with firebase - firebase

Question

In my case, the notification only arrives on the device from which the new item in the list has been added, other users do not receive the notification. I would like other users to receive notifications. Currently I'm using the topic (the same case is with the device token).
Here is my code...
This is my function for post notification on firebase server:
Future postNotification() async {
final postUrl = 'https://fcm.googleapis.com/fcm/send';
final data = {
'to': '/topics/weather',
"collapse_key": "type_a",
"notification": {
"title": channel.name,
"body": channel.description,
},
};
final headers = {
'content-type': 'application/json',
'Authorization':
'key = myserverkey'
};
final response = await http.post(
Uri.parse(postUrl),
body: json.encode(data),
encoding: Encoding.getByName('utf-8'),
headers: headers,
);
print(response.statusCode);
}
For this global functions I get response status code 200 and everything look's fine, for topic name in this example I use weather.I call this function when adding a new element to the list.
This is my function for show notifications and I use this function in home screen of my app:
void showNotification() async {
flutterLocalNotificationsPlugin.show(
0,
channel.name,
channel.description,
NotificationDetails(
android: AndroidNotificationDetails(
channel.id,
channel.name,
channel.description,
importance: Importance.high,
color: Colors.blue,
playSound: true,
icon: '#mipmap/ic_launcher',
),
),
);
}
This is how I call the show Notification function on the home page of my application:
#override
void didChangeDependencies() {
super.didChangeDependencies();
FirebaseMessaging.onMessage.listen((RemoteMessage message) async {
RemoteNotification notification = message.notification;
AndroidNotification android = message.notification.android;
if (notification != null && android != null) {
final messageTitle = message.notification.body;
FirebaseMessaging.instance.subscribeToTopic('weather');
showNotification();
print(messageTitle);
}
});
}
Do I need an extra backend to make this work on other devices as well?