It shows like this .
Now I cannot get out of this login screen
What DE, what DM, what image?
Its SDDM. And apparently theme “WhiteSur”.
And … you either chose a broken theme … or it is malformed or installed incorrectly.
How did you install the theme ?
Once you type your password and press Enter doesn’t load the desktop?
If you still have troubles, switch to TTY3 for example by pressing Ctrl+Alt+F3 then log in as your user, provide the password, then type:
sudo nano /etc/sddm.conf.d/kde_settings.conf
provide your password again
Then press Ctrl+O (that is o not 0) to save, then press Ctrl+X to exit. Then reboot the system with:
You should have a working SDDM now.