Login with iPad Air works in Simulator but Apple says it doesn't

• Device type: iPad Air (5th generation)
• OS version: iOS 17.5

I don't know what to do.. I am using Firebase for auth and it work on every device. Except for the iPad Air. Does somebody have a similar issue?

    try {
      String email = _emailController.text;
      String password = _passwordController.text;

      if (EmailValidator.validate(email)) {
        await _auth.signInWithEmailAndPassword(
            email: email, password: password);
      } else {
        print("Ungültige E-Mail-Adresse");
      }
    } catch (e) {
      print("Anmeldefehler: $e");
    }
  }
}