Ok, so I found out what was wrong. I'll make a note for others regarding the cause just in case. So, basically, after reinstalling the drivers to the mentioned version, it turns out that after removing displays and previous driver versions using Display Driver Uninstaller, DDC/CI switched off in my monitor OSD. Communication between the monitor and GPU was turned off and that is why Adaptive Sync was visible as not supported in Radeon Settings. Now that I switched DDC/CI on, everything is back to normal. No clue how could that happen in the first place.