A facebook employee explained me how tracking works. Its not the email address Meta is concerned about. Its the IP, device identifiers and location. Meta doesnt care about the email at all apart from sending you emails for notification. Even with a fake email they exactly know who you are. Let's say you visit CNN.com which has facebook tracker. Facebook has the IP and the device identifiers. Now you login with fake email account on Instagram, facebook knows that's the IP ans the same device hence it "must" be the same person That's how facebook creates shadow profiles.
I dont have facebook, and I explicitly tell family not to put my pictures on their facebook pages or mention me at all.
I'm still 100% convinced facebook has my biometric data, my home address, and what I ate for dinner last week.
The amount of data they collect is insane, and intrusive.
Every time it comes up, i'm reminded of a sex worker who was doxed by facebook because she in a parking lot that a former client was in, and it had used proximity data and shit to link her Sex Work Phone/Facebook Account, to her real Phone/Facebook account, which was then given to the client as a suggested contact.