Earlier quoted context omitted.
Facebook maintains “shadow profile” accounts for people who have not personally made an account [1], the answer to your question is “whatever information your friends and family exposed on your behalf and which is linkable to you”. [1] https://medium.com/@SpiderOak/facebook-shadow-profiles-a-pro...
so you think they are confident enough to link somebodies randomly created alias, let's say "InteretDude420" to a real name? What if opened a VR Arcade and owned 100 Oculus Quests and made 100 separate accounts?
Matching all that data to the real information you just ran through paypal or other merchant (some merchants sell this data directly) is something an intern can do on their first day.
I thought they denied maintaining shadow profiles though? There seems to be some people at FB who actually care about getting this stuff right and doing the right thing but economic forces at this point appear to be pushing most of the company in a very different direction.