"mandela effect" is a psychological operation, likely from the organization Tavistock.

Things that groups of people easily mis-remember is not evidence of reality being "overwritten" or anything. It's much much more likely lots of people just mis-remembered these things because they're things that are easy to mis-remember. Simple as that. The whole thing, along with flat earth, is just a pure distraction from anything of importance. That's the whole purpose of Tavistock.