Unity feels like it runs best on Windows to me. Metal bugs caused quite a few Unity issues for me when I was developing on a Mac. That was a year or so ago, so maybe the situation has improved.

Also a lot of useful 3d content creation software is Windows only, or only supports CUDA acceleration, so implicitly rules out Mac from being a first class citizen (e.g. substance painter)

Obviously not every game is the same, or needs fancy tooling. But Windows feels like it just works for game dev.