Maybe an unexpected regression with the recent upgrade to The FreeBSD Forums, there's no longer an OP hint on screen.
This issue was first noticed whilst seeking historical posts by Zagzigger:
13.1 update: now user cannot log in to KDE, but root can
System updated many times (probably from 12.0) now refuses to run KDE as user. After stopping SDDM, I'm able to log in as either user or root via a terminal using startx, but KDE will only allow a login from root. When in the KDE root screen, the user can be seen but not altered. The user...
forums.freebsd.org