New user registration impossible

hello everyone,
I already had this problem a month ago which was solved by updating the plugin to a different version. It is impossible to register for new users. If they are added by the admin from the control panel, then they can login without problems. I tried to deactivate all the plugins and themes and the problem persists. I’m linking you to the previous conversation (I’ve already tried installing another version of the plugin):

https://ww.wp.xz.cn/support/topic/user-registration-impossible/

The page I need help with: [log in to see the link]