I tried to log in to the forum using credentials dating back to 2018, as saved in my password vault. The login form said that no such user existed.
I then tried to create a new user against the same email address and submitted the form. A blank form was displayed again. There was no error message. No message was shown to the effect of 'your login has been created -- you'll be sent an email with a confirmation link'. No confirmation email was received either.
I'm opening a second bug with respect to the website contact form, as that didn't work either.
Mail email@example.com with sign up details (username, email, IP address(es)).