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 don’t know if it is the case here, but uBlock Origin lets some trackers through and redirects them to empty addresses, so they are effectively useless, good as blocked. This is done so the website doesn’t detect that you blocked the tracker, in order to avoid breaking website functionality.
That definitely makes sense.