Is it a bug?
And should I also be worried about the Refresh Rate not being auto set to its highest value?
What monitor do you have? Does it really have that resolution or is this just a cinema format support thing? I can set my TV to 4096x2160 resolution but that doesn’t mean I should or would want to. The TV is still just a UHD TV, meaning 3840x2160 pixels.
Unclear if I got your model exactly right, but your TV most likely has a native resolution of 3840x2160 and thus that’s what the default is:
4096x2160 is the TV reporting this resolution as supported (which internally is cropped afterwards) to support more devices which might require that resolution for - as I said - the cinema standard 4K which is 4096 pixels wide:
If you want 1:1 resoultion, use the default of 3840x2160.
Does this also mean that the Refresh Rates are automatically increased when available?
It should, yes.
Although it looks at resolution first and chooses the largest one available and from there, looks for the best refresh rate:
If your display supports 2K 240Hz and say 4K 120Hz, kscreen will always choose 4K 120Hz, but choose that over other modes with the same resolution, e.g. 4K 60Hz.
EDIT: Looking at the code a bit more in detail, one exception is there: If the refresh rate for a suitable resolution is available in less than 50Hz only, it will default to a lower resolution which supports at least 50Hz, as in src/outputconfigurationstore.cpp · a651ac0b4134a19ca9b85ae42fc64cc41860c152 · Plasma / KWin · GitLab .
That behaviour is as expected if you ask me.
You can see the technical details of your TV resolutions uses the command kscreen-doctor -o.