Thanks to fraschm#4025 on Discord, the program might be working again. I have not yet compiled a release myself, but the code on Github should be working (I have not tested it).
Apparently the issue was easier to fix than I thought. All we/I had to do, was update the site key I provided when requesting a captcha solve.
Will remove all username features soon, as you now have to set a name ingame instead of upon creation.