Please search for the proper option in AMD Adrenalin for your game (make sure you have a fresh version of it).
"Fluid Motion Frames 2"
Or there is a non-free software for that purpose on Steam (but the game should be ran in borderless window mode)...
I had terrible issues (different from yours) after switching to 4K gaming.
They were completely fixed by just enabling paging file in Windows settings.
I broke my head searching for reason in my RX 6800 Nitro+
3+ years using LG OLED CX 65" + PC and no Burn-In problem (at least noticeable). Using it for movies/gaming/websurfing with all OLED protection settings ON ~MEDIUM.
And still (after these 3 years) catching myself thinking it is perfect
Here is reference photo of what I experienced before bying...