No 4K 120fps with pc

Hey,

I have PC with RTX 3080 that have hdmi 2.1 and I don’t know why but when I am activating game mode I can’t get more than 1080p60hz.

When I disable It I can get 4k120hz. I saw many problems came with new tizen update but I can’t be for sure because I was not using PC for gaming for a long time. Can someone help me with that?