"A character with this name already exists"

Just bought the game, but I can't create a character, because whatever name I pick, no matter how weird, I get the message that the name already exists.

I think I tried about 20 different names, some really weird ones, with wordplays exclusive to the Dutch language, but no avail. Can't add special characters or numbers either, because those aren't allowed.
This is the first game ever where I run into this issue to this extend: Other games might have my first choice taken, but every single thing I try, to the point I can't make a character at all, in a game that is still in early access no less? I don't believe this. I believe there is something else going on.

Anyway, I'd like to play the game I just bought. Any tips?

i add _ or __ to end of name, it works