Fun story.
At my previous company we had "Sign in with Facebook" – whatever your opinions on it are, it was probably the right thing for the company at that time.
Facebook decided to "audit" us to make sure we were doing sign in right. The tested it incorrectly, told us we were at fault and needed to fix it, and gave us 2 weeks to do so. We scrambled to figure out what the issue was, only to find after they eventually replied to our emails (all they told us up-front was "it doesn't work") that they had tried to use a sign-in only button to sign-up, similar on many websites, not at all for our flow and not something it was possible for us to do. We explained this and they dropped the audit.
2 weeks later, they audited us again, failed us again, and gave us a deadline to fix it. We replied pointing to the previous case and explaining again why it was working. We never heard back.
2 weeks later, they audited us again, failed us again, and gave us a deadline to fix it. We replied asking what the hell was happening (politely). We never heard back.
1 week later "Sign in with Facebook" stopped working with no other warning. We opened a support case, we emailed our ads account manager, we emailed our previous ads account manager as the first was on holiday, and all we got was "we're looking into it, but it looks legit, fix it".
I asked for a call and explained that the current user experience for users was that they would click "Sign in with Facebook" and see an error saying "Facebook is currently not working, please sign in another way", and that the only way we had to resolve this was to email all our Facebook auth'd users a password reset with an explanation that Facebook sign in no longer worked, and to then remove the feature from our site.
"Ah. Ok yeah let me see what I can do". It was working about 2 hours later, and we weren't audited again in the rest of the time I was at the company.