[REQUIRED] Please fill in the following fields:

• Unity editor version: 2020.2.7f1
• Firebase Unity SDK version: 8.7.0
• Source you installed the SDK: unitypackage (.unitypackage or Unity Package Manager)
• Problematic Firebase Component: Auth (Auth, Database, etc.)
• Other Firebase Components in use: _____ (Auth, Database, etc.)
• Additional SDKs you are using: _____ (Facebook, AdMob, etc.)
• Platform you are using the Unity editor on: Windows (Mac, Windows, or Linux)
• Platform you are targeting: Android (iOS, Android, and/or desktop)
• Scripting Runtime: IL2CPP (Mono, and/or IL2CPP)

[REQUIRED] Please describe the issue here:

I use this example to log in apple id on Android.

Firebase.Auth.FederatedOAuthProviderData providerData =new Firebase.Auth.FederatedOAuthProviderData();
providerData.ProviderId = "apple.com";
providerData.Scopes = new List();
providerData.Scopes.Add("email");
providerData.Scopes.Add("name");
Firebase.Auth.FederatedOAuthProvider provider =
new Firebase.Auth.FederatedOAuthProvider();
provider.SetProviderData(providerData);
auth.SignInWithProviderAsync(provider).ContinueOnMainThread(task => {
if (task.IsCanceled) {
Debug.LogError("SignInWithProviderAsync was canceled.");
return;
}
if (task.IsFaulted) {
Debug.LogError("SignInWithProviderAsync encountered an error: "
task.Exception);
return;
}

Firebase.Auth.SignInResult signInResult = task.Result;
Firebase.Auth.FirebaseUser user = signInResult.User;
Debug.LogFormat("User signed in successfully: {0} ({1})",
    user.DisplayName, user.UserId);

});

Everything works fine on Android. But when I pull up the authorization page and click the home button, I go back to my game from the desktop.Then when I call SignInWithProviderAsync again in the same way, I get an error ：

SignInWithProviderAsync encountered an error: System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. ---> Firebase.FirebaseException: A headful operation is already in progress. Please wait for that to finish.
--- End of inner exception stack trace ---
--- End of inner exception stack trace ---
---> (Inner Exception #0) System.AggregateException: One or more errors occurred. ---> Firebase.FirebaseException: A headful operation is already in progress. Please wait for that to finish.
--- End of inner exception stack trace ---
---> (Inner Exception #0) Firebase.FirebaseException: A headful operation is already in progress. Please wait for that to finish.<---
<---
UnityEngine.Logger:Log(LogType, Object)
MobileLoginService:b__13_0(Task1) System.Action1:Invoke(T)
Firebase.Extensions.c__AnonStorey9:<>m__0()
System.Func1:Invoke() Firebase.<RunAsync>c__AnonStorey11:<>m__0()
System.Action:Invoke()

(Please list the full steps to reproduce the issue. Include device logs, Unity logs, and stack traces if available.)

Steps to reproduce:

Have you been able to reproduce this issue with just the Firebase Unity quickstarts (this GitHub project)? Yes.
What's the issue repro rate? (eg 100%, 1/5 etc) 100%

What happened? How can we make the problem occur?
This could be a description, log/console output, etc.

1. Download and configure this github project to make it run

2. Modify the SignInWithProvider function:
   protected void SignInWithProvider(string providerId) {
   var providerData = new Firebase.Auth.FederatedOAuthProviderData();
   providerData.ProviderId = "apple.com";
   providerData.Scopes = new List() { "name", "email" };

      var provider = new Firebase.Auth.FederatedOAuthProvider();
      provider.SetProviderData(providerData);
      
      auth.SignInWithProviderAsync(provider).ContinueWithOnMainThread(signin_task => {
      if (LogTaskCompletion(signin_task, "SignInWithProvider")) {
        DebugLog("SignInWithProviderTask Completed:"   signin_task.IsCompleted);
      }
   
      if(signin_task.Exception != null) {
        DebugLog("SignInWithProviderTask - Exception: "   signin_task.Exception.Message);
        return;
      }
   
      DisplaySignInResult(signin_task.Result, 1);
   

   });
   }

3. Click SignInWith | Miscrosoft, open the browser and click the home button to return to the Android desktop, click app to return to the application, and click SignInWith | Miscrosoft again.

If you have a downloadable sample project that reproduces the bug you're reporting, you will
likely receive a faster response on your issue.

Relevant Code:

// TODO(you): code here to reproduce the problem