This is the native resolution of the monitor and the system can clearly run on that resolution based on a previous screenshot you provided.
Is there any reason you want to run your desktop on 1920x1080?
Edit: Apparently I have no idea what your are trying to do and I don’t even get what is your issue. Sorry for the trouble and the misunderstanding. It’s better for me to shut up now 
The xorg config files has nothing to do with the resolution, leave it as is.
But I wonder why you change the resolution in the nvidia settings and not by right clicking the desktop and selecting “configure display settings”.
I experienced something similar to what you describe, my bar was showing, but my desktop was scrollable (outside of the screen). It acted differently between x11 and wayland.
IIRC it had to do with scaling in the plasma display configuration. Try playing around with it between 90-110% and see what changes.
I now see there is also a setting for overscan, but that is probably not connected to this.