Question Monitor (TV) looks washed out at 4k res, more vibrant/saturated at 1440p

[_dawn_chorus_]

TL/DR: My 4k TV/monitor looks great at 1440p, vibrant and nicely saturated/contrasted. But when I up the resolution to 4k, everything looks a bit washed out.
What could be causing this?

I've been using a Samsung Q60 55" 2018, or maybe 2019, for the past couple years as my main monitor. I have always had the resolution set to 1440p to get higher refresh rates in games, and frankly the difference in image wasn't very noticeable from the 4-5 feet I sit from it. Except for text that is. My aging eyes just discovered how much better 4k looks for text, but sadly for some reason the colors become washed out.
Strangely if I open a game while the desktop is in 4k, it will look washed out, but if I change the in game res to 1440p the colors pop, despite the desktop res remaining the same.
What could be causing this?

TV plugged directly in GPU via HDMI

 

[Darkbreeze]

Make sure that with the display output set to 4k, the dynamic range is set to FULL. Even if that turns out to not be the problem, I'm betting this is a setting somewhere and not an actual physical problem.

https://imgur.com/aEnlBkH

View: https://imgur.com/aEnlBkH


What are your full hardware specs?

 

[_dawn_chorus_]

Make sure that with the display output set to 4k, the dynamic range is set to FULL. Even if that turns out to not be the problem, I'm betting this is a setting somewhere and not an actual physical problem.

https://imgur.com/aEnlBkH

View: https://imgur.com/aEnlBkH


What are your full hardware specs?

Thank you for the suggestion and apologies for my very late reply.
For some reason it is indeed locked to "limited" when switched to 4k. The button is greyed out and I cannot change it. The Output color format is also unchangeable and is YCbCr420.

When I switch back to 1440p/120hz I can change all of those settings and by default the color format is RGB and the dynamic range is Full.

I am using an HDMI cable to connect to my GPU. Could it be a limitation of the cable?
Link to cable: https://www.amazon.com/gp/product/B01N22LFPL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I also can't find anything in the TV's RTINGS review that suggests this limitation.
https://www.rtings.com/tv/reviews/samsung/q60-q60r-qled

UPDATE: If I switch it to 30hz in 4k then it changes the output to RGB and the range to full but they remain locked. However I'm not a barbarian, and 30hz will not do, so still looking for a fix.

Full system spec is:
i7-8700k
1TB 970 evo m.2 boot drive
Gigabyte Aorus Pro Z390
32GB 3600 cl16
3080FE
Corsair rm850x PSU
4x 1TB 860 evo ssd's
a 4TB WD Blue

 

[drivinfast247]

Make sure to set the TV HDMI port to "enhanced*" in the settings menu.