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've been using a VPN for several years. I've tried using every major browser except Mulvad and Librewolf. As far as I can tell, they're doing some form of digital fingerprinting that I can't block. My only option would be getting an entirely new computer. I went through and overwrote/deleted 15 years of comment history (but have not deleted accounts), it's just not worth it to me.