Flutter FCM Notification Works on Android however Fails on iOS with 400 Error (DioException)

I’m utilizing Flutter to ship push notifications through Firebase Cloud Messaging (FCM) utilizing the HTTP v1 API. The notification works nice on Android, however I’m getting a 400 (dangerous request) error when sending to iOS units. Beneath is the code I’m utilizing:

Future sendNotificationF() async {
strive {
String? accessToken = await CommonMethods.getAccessToken();
remaining _dio = Dio();

    // Set FCM HTTP v1 headers
    _dio.choices.headers = {
      'Content material-Kind': 'utility/json',
      'Authorization': 'Bearer $accessToken',
    };
    
    FirebaseMessaging messaging = FirebaseMessaging.occasion;
    String? token = Platform.isAndroid
        ? await messaging.getToken()
        : await messaging.getAPNSToken();
    
    if (token == null) {
      print("Error: Couldn't retrieve FCM token.");
      Fluttertoast.showToast(
          msg: "Error: Couldn't retrieve FCM token.",
          toastLength: Toast.LENGTH_LONG);
      return;
    }
    
    var information = {
      "message": {
        "token": token,
        "information": {
          "title": "Hiya",
          "message": "This can be a notification message.",
          "physique": "That is the physique content material.",
          "sound": "notification_chat",
        },
        "notification": {
          "title": "Hiya",
          "physique": "That is the notification physique.",
        },
        "android": {
          "precedence": "excessive",
          "notification": {
            "sound": "notification_chat", // Customized sound for Android
            "channel_id": "astrosane",
          },
        },
        "apns": {
          "payload": {
            "aps": {
              "sound": "notification_chat", // Customized sound for iOS
            },
          },
        },
      }
    };
    
    remaining response = await _dio.publish(
      'https://fcm.googleapis.com/v1/tasks/project-ID/messages:ship',
      information: jsonEncode(information),
    );
    
    print("Notification despatched efficiently!");

} on DioError catch (e) {
print("Notification error: $e");
Fluttertoast.showToast(msg: e.response?.information.toString() ?? "An error occurred", toastLength: Toast.LENGTH_LONG);
}
}

Error
{error: {code: 400, message: The registration token isn’t a legitimate FCM registration token, standing: INVALID_ARGUMENT, particulars: [{@type: type.googleapis.com/google.firebase.fcm.v1.FcmError, errorCode: INVALID_ARGUMENT}]}