Bug 486851

SUMMARY
Hi everyone, I am facing a problem with plasma 5.27.7. I am making actually my own distro. I almost finished my package manager. I can boot a full plasma desktop environment, with Openrc. I am facing a problem I can't solve:

If I generate a new user by CLI in a terminal, with the useradd command, the new user is not visible in the plasma settings GUI.

But if I generate a new user by the plasma settings GUI, the new user is visible in that graphical user list. 

I have another problem as well. It's related when I try to change the sddm theme. If I try to apply to plasma settings, I have this error: "The backend does not specify how to authorize". If I change the resolution as well and I reboot, it come back to the default value, and not the one I setted.

I did 2 screenshots to make you understand: 
https://zupimages.net/up/24/19/f7cp.png
https://www.zupimages.net/up/24/19/oc7s.png


STEPS TO REPRODUCE
1. Login with a user generated by useradd command (not by the graphical user settings)
2. Try to change the resolution, SDDM theme and see the user list

OBSERVED RESULT
Even I confirmed the resolution change, at the reboot come back to the default value was before, I can't see any user generated by CLI and I can't apply the settings for SDDM.

EXPECTED RESULT
I am able to see all users, and to change whatever I want in the settings

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Linux Kernel 6.5.1 / Plasma 5.27.7
(available in About System)
KDE Plasma Version:  5.27.7
KDE Frameworks Version: 5.109.0
Qt Version: 5.15.10

ADDITIONAL INFORMATION
If I login with a user generated by CLI or by the plasma GUI, I have the same result, I don't see any user and I can't change special settings like resolution or sddm theme. But normal settings like cursor themes can be changed