Thanks for looking into it. After having problems with a couple other games, I posted about it and there's a little discussion going. I think we've figured out that it's a Chrome update issue, and not something you'll be able to fix for macOS users until Chrome fixes it (or unless you're willing to remove all shaders from your game, which is what I just did for an old game that was broken by this).
I haven't figured out why everything is broken in Safari, as that seems to be a separate issue. I don't know if it's a recent change, as I haven't used itch.io on Safari before now, when I started having issues with Chrome. My understanding is that Safari is less compatible in general. For your game, it runs but at an unplayable 4fps in Safari. Many others are entirely broken, which they may always have been due to the macOS WebGL2 incompatibilities.
It is often difficult to know whether something is a problem in our hands, or on the game engine to fix, or the browser, the operating system, the universe itself...