Facebook has a new AI system that has been incorrectly flagging and disabling ads and ad accounts. They send out notification emails like this:
In the email, it doesn't really tell you why the account has been disabled. And to confirm, you will want to check out the account quality section here: https://www.facebook.com/accountquality and go to the Facebook account tab.
In this example, the account was restricted because the two-factor authentication (2fa) wasn't enabled. Click on 'Secure Your Account' on the right and proceed with the steps to set up two-factor authentication.
Note: your account might be restricted for other policy violations, click on 'Submit Review Request' on the right and proceed with the process to request an account review.
There are three options to secure your Facebook account and we recommend the SMS option.
Text Message (SMS)
Click on 'Use Text Message (SMS)' box and follow the prompt to confirm your phone number, receive a text from Facebook, enter the 6 digit code and now your two factor authentication is all set up!