This is the same in Win 10 and Win 11. its a known issue with 4K screen using Windows which Microsotf didnt bother to handle. you could have researched a bit before answering as not every question here related to Powershell cleaning commands or computer Restart (i hate those generic Tech support script answers).
They have fixed thumbnail pixel size generated in cache, they should work in a new system which the thumbnail actually adjustable and not just replaced. maybe they can add a 4k thumbnail catagory. this issue is dragged for years and make it hard to work.