As of now, a KDE user account needs registering on KDE identity which do not have a standard 2FA option such as TOTP and FIDO2 security rather some spreadsheet.
To log in to KDE Discuss, it requires KDE invent which needs to be first created. Then, log in. KDE Invent is for developing KDE apps not login management.
I also do not see a way to integrate KDE Identity app to KDE Bugzilla. Require two separate password entries that get messed up because of base domain, need to adjust regex because of it.
KDE identity is meant to be used for logging in into GitLab, Forum, Wiki and Bugzilla not the GitLab one meant for developing.
Also, there is no proper way to request for deletion of KDE identity account as far I have seen.
Regarding username change. I understand it’s crucial. But I think you should have a git version for username change, that only KDE Sysadmins could see for the sake of security purposes. Allowing the user to change username at will and if in case of imposing a Ban it should be done based on account ID.
I would like to see an approach similar Fedora Accounts system in KDE.