Flutter firebase_messaging . Receiving the data message after device reboot

I am using firebase_messaging package to get data messages from server.

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  print('FirebaseMessaging handles background message: ${message.messageId}');
  await Firebase.initializeApp(); 
}

FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

When user reboots the device, the app is still able to receive pushes on Android, but not on iOS. does anyone know is it expected behaviour or my integration is wrong? Thanks