Recently I wanted to have a look at a few ex coworker profiles (who are not my friends on FB). I didn't want to use my personal account because then it suggests me to them (something I wanted to avoid, as I'd not been in touch with them for almost a decade).
1. I created a VM (Ubuntu 18.04 + Firefox + uBlock -> enabled everything in uBlock).
2. Tried to create an Fb account -> asks for phone number. I didn't want to be identified so I could not continue.
3. Tried another way to create a new account -> success.
4. Fb obviously tried to figure out who I am -> was unable to do so at that point -> Forced me to post a picture of myself (and suspended my account until I did and they verified it).
5. Posted a made up picture and got past the first hurdle
6. Fb asked me for a phone number -> Logged out and used another means to log in.
7. Fb locked my account and asked for another picture (did similar in Step 5 once again)
8. Looked up my ex co-workers.
9. Until now, I've not been identified, I looked up a friend's profile (this friend is also my personal friend on Fb). FB immediately identified me and showed up my entire friends list as suggested friends).
10. I immediately tried to delete that profile (took 30+ days and they asked for Govt ID).
I've had multiple fake FB accounts, and FB's fingerprinting and data sharing is insanely crazy - I recently logged out of one my fake accounts on iOS via Safari Incognito (no FB app, Safari is always used as incognito) - it showed my personal phone number in the log in field.