When I click the screen resolution drop down to select another resolution I confronted with resolutions such as 192...080 instead of 1920x1080. I'l attach screenshot. Reproducible: Always
Created attachment 99753 [details] screenshot
Is this issue also visible, if you are using a different widget style? Try running "kcmshell5 -style Fusion kscreen" in Konsole.
It's not an issue when I run your command as the drop down list then seems to be dependent of the width of the dialog. I'll add a screen shot. Just now I realize that the resolution widget is different for my laptop screen and for my external screen. On the laptop it's a drop down, on the external screen it's a slider. My guess is that it's because the laptop has more options.
Created attachment 99762 [details] screenshot, other widget style works
*** Bug 361204 has been marked as a duplicate of this bug. ***
*** This bug has been marked as a duplicate of bug 403153 ***