Why is the notification sent from firebase is getting delay in receiving

Below is the code for listening notification in flutter i am sending a notification from firebase console

    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      RemoteNotification notification = message.notification;
      AndroidNotification android = message.notification?.android;
      if (notification != null && android != null) {
        flutterLocalNotificationsPlugin.show(
            notification.hashCode,
            notification.title,
            notification.body,
            NotificationDetails(
              android: AndroidNotificationDetails(
                channel.id,
                channel.name,
                channel.description,
                color: Colors.blue,
                playSound: true,
                icon: 'ic_launcher',
              ),
            ));
      }
    });