您可以将输入显示为灰色，并禁用提交"按钮，直到.onAuthStateChanged解决问题的速度非常快，通常不到1秒.也许在登录表单上放置了线性进度指示器?

You could grey out inputs and disable submit button until .onAuthStateChanged resolves which happens very quickly, usually in under 1 second. Maybe put a linear progress indicator on the login form?