@garrett okay, this is crazy.
So the correct one as far as I know is "krita AT mastodon DOT art". But I've tried twice to send that to you and seemingly the input box changes the Toot to "Krita AT mastodon DOT art".
I didn't realize usernames are case sensitive and that you can't type lowercase ones.
A server setup for the users of gould.cx to connect to the greater ActivityPub network.