flutter firestore not creating a document in the cloud firestore database

This is very weird as creating a doc in the firestore database is a fairly easy and straightforward process. However, my doc is not being created. So, after user pays a fee the app created the records in the auth table in firebase, which works fine. Then it shoud create a record in the firestore. Here is the payment success screen, which should redirect to the other screen, but it just stuck there:

class PaymentSuccess extends StatefulWidget {
final String? email;
final String? password;
const PaymentSuccess( {Key? key, this.email, this.password, }) : super(key: key);

@override
State<PaymentSuccess> createState() => _PaymentSuccessState();
}

class _PaymentSuccessState extends State<PaymentSuccess> {
@override
void initState() {
super.initState();

WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
  LoginViewModel viewModel = Provider.of<LoginViewModel>(context, listen: false);
  viewModel.signUp(context, widget.email!, widget.password!);
});
}

@override
Widget build(BuildContext context) {

return Scaffold(
  backgroundColor: Colors.transparent,
  body: Stack(
      children: <Widget>[
  Container(
  decoration: const BoxDecoration(
  image: DecorationImage(image: AssetImage("assets/images/background.png"),
  fit: BoxFit.cover,),
),
),
Container(
    alignment: Alignment.center,
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        const Icon(Icons.check_circle_rounded, color: Colors.green,size: 150,),
        const SizedBox(height: 25,),
        Text(Languages.of(context)!.paymentSuccess,
          style: const TextStyle(fontSize: 25, color: Colors.white),),
        const SizedBox(height: 20),
        Text(Languages.of(context)!.plsWait,
          style: const TextStyle(fontSize: 20, color: Colors.white),),
      ],
    ),
  ),
 ])
 );
 }
 }

the LoginViewModel class' signUp method:

signUp(BuildContext context, String email, String password) async {
loading = true;
notifyListeners();
try {
  UserCredential userCredential= await FirebaseAuth.instance
      .createUserWithEmailAndPassword(
      email: email, password: password);

debugPrint('userID -------> ${userCredential.user!uid}');

  await usersRef
      .doc(userCredential.user!.uid)
      .set({
    'id': userCredential.user!.uid,
    'email': email,
    'profilePic': '',
    'username': 'User',
    'isPaid': true,
    'timestamp': Timestamp.now()
  });
  loading = false;
  notifyListeners();
  Navigator.pushReplacement(context, MaterialPageRoute(builder: (_) =>
  const EditProfile()));
}on FirebaseAuthException catch (e) {
  loading = false;
  notifyListeners();
  errorDialog(context, e.message!);

} catch (e){
  loading = false;
  notifyListeners();
  errorDialog(context, e.toString());
}
}

So, as was mentioned earlier the method does create the user in the authentication, but it does not set data in the firestore collection. I did create collection with some dummy doc and id field in it.

the debugPrint does printes the credentials, but then it stops working further....

I dont understand what I am missing here... The internet is stable and fast. Help appreciated very much!

I do get the error:

W/Firestore(11015): (24.2.2) [WatchStream]: (193087b) Stream closed with status: Status{code=UNAVAILABLE, description=Channel shutdownNow invoked, cause=null}.

but my rules are very simple:

service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
  allow write: if request.auth.uid != null;
  allow read: if request.auth.uid != null;
    }
  }
}