我也经历过类似的事情，希望这能有所帮助：
要从Unity中的Firebase身份验证响应获取JWT令牌，您可以使用SignInWithEmailAndPasswordAsync（）方法返回的User对象并访问User.Token属性。
JWT标记：

private IEnumerator Login(string _email, string _password)
{
    //Call the Firebase auth signin function passing the email and password
    var LoginTask = auth.SignInWithEmailAndPasswordAsync(_email, _password);
    //Wait until the task completes
    yield return new WaitUntil(predicate: () => LoginTask.IsCompleted);

    if (LoginTask.IsFaulted)
    {
        //Handle error
        Debug.LogError("Error logging in user: " + LoginTask.Exception);
    }
    else
    {
        //User is now logged in
        //Now get the result
        User = LoginTask.Result;
        Debug.LogFormat("User signed in successfully: {0} ({1})", User.DisplayName, User.Email);
        warningLoginText.text = "";
        confirmLoginText.text = "Logged In";

        // Get the JWT token
        string jwt = User.Token;
        Debug.LogFormat("JWT token: {0}", jwt);
        // Do something with the JWT token, such as sending it to a server for verification
    }
}

值得注意的是，令牌的生存期为1小时，超过此期限后您必须刷新它。