> * Person used characters that you no longer want to accept in nicknames

Why would you refuse certain characters? My last name contains a dash and one letter with a diacritic. I am beyond tired of playing whack-a-mole trying to guess what rule I violated with my "invalid name."

And fuck companies who have the gall to call my name "invalid" to my face, too. Have some thought before you write an error message. "Contains an invalid character" wouldn't be insulting, for example.