好，我得到了答案.在剑桥分析之后，除非您的应用程序在Play商店中上线，否则您无法公开使用fb登录.您仍然可以在开发人员模式下测试登录功能.那就是为什么只有我才能登录其他人.为了让其他人使用，您必须将它们添加为developer.facebook.com中的测试者.如果您的应用程序已经上线并且想要添加此类功能，还请确保先更新隐私权政策网址.

Ok i got the answer. After that cambridge analytica you cannot use fb login publically unless your app is live on play store. You can still test the login functionality in developer mode. Thats why only i am able to login not others. For others to use you have to add them as tester in developer.facebook.com . Also make sure to updated privacy policy url first if your app is live and wants to add such functionality.