Good afternoon! Help me figure out the forum. This is the problem of a specific user or something else?
The users did not have a username and the system set automatic them?
Can you share more detail or context about what the image is about?
Did you have any weird third party plugins installed? I remember Babble doing something odd like this.
Okay, try loading your site in safe mode, or uninstall Babble (and possibly other non-official plugins) one by one, reloading/rebuilding your Discourse app afterwards and see if any of these help.