My app has been restricted for creating a negative user experience that is in violation of our Platform Policies.
I got an alert saying this in my facbook developer account. And new user are not able to login with Facebook in my app. I'm not sure what should be the next step now or where to look in the Facebook developer dashboard.
All information should be include in the respective notice you received. If there are any steps/actions required from you, or if there's an option to appeal, these are also mentioned in that notice.