Here's a picture of my login screen. (Please excuse the Moiré bands; it's an actual photograph.)It doesn't look anything like the images inSystem Settings->Startup and Shutdown->Login ScreenNote, in particular, the X-Windows style X shaped cursor.
It seems that part of a theme is missing; but I have no idea what it could be.
Thanks - jon
I'd try to reinstall the group "Workstation" to solve anything missing/lost
dnf groupinstall "Fedora Workstation"
and perhaps the desktop (like "GNOME Desktop Environment") or
what you use