I think I remember using switchresx on my older 2005 mini to get the resolution I wanted on an old TV with a composite video adapter thingy, but apart from that, it’s usually down to the TV/Monitor, what it’s reporting via EDID information back to the computer. Not all TVs do this properly.
As for the OP, I don’t know what is his issue, but I would point my finger at the AMD video drivers. Apple is not responsible for these on Windows.