Thanks for that suggestion.
So I’d create a new user account, change ownership of all posts to the new user and change all references (which shouldn’t be a problem with the usernames paul(a)kreuzer, but if someone answered things like “Hey Paul, …” that would stay untouched)?
I’m not really sure what steps 2 and 4 do.
Also:
This would be a problem.
PS:
What if I just changed my username (paulkreuzer -> paulakreuzer) and create a new user with the old username (paulkreuzer)? Would quotes and mentions then show that new user?
Then I could enter a redirection into that new user’s description and maybe it’s somehow possible to disallow mentioning that user in the future?