I will assume this is MV (as the other makers aren't supported on Mac).
This is not a bug. Unless part of your screen is missing and is there on other platforms, it simply means that your mac doesn't have the same aspect ratio than your game. Check the resolution on your mac, and compare it to your game's resolution.
Made a brief video showcasing early game play... Got a copyright claim by BIG UP! (https://big-up.style/) for using music I bought from here (Future Steam Punk Pack). Now I wonder if I should strip any purchased music from here out of my game.