When I set my mini PC to 4K 60Hz, it switches to 4K 30Hz after a few hours and then disappears from 60Hz. I’m currently running Windows 11, and I downloaded the driver from the Chuwi FourM. I bought it as an HTPC and used it on an FHD TV for about two years before switching to a 4K TV a while ago. I also tried a fresh install of Windows 11. I didn’t install AMD Adrenaline.
I think I found the answer by myself. The problem is because of the MS driver. It got messed up when it was automatically updated with the AMD driver made by MS. There’s no problem after I stopped updating the MS driver with gpedit, so far.