Anecdotally my own experience is consistent with this with the same platform+browser combination.
It appears that there are now significant numbers of sites - or at least noticeable parts or features of sites - that rely on Google-specific APIs and haven't been tested on other browsers.
However visiting those sites from Apple devices is often similarly frustrating. I'm not sure this is an anti-Firefox thing. It seems more of a not realising there are other browsers apart from Chromium-based ones thing.
It appears that there are now significant numbers of sites - or at least noticeable parts or features of sites - that rely on Google-specific APIs and haven't been tested on other browsers.
However visiting those sites from Apple devices is often similarly frustrating. I'm not sure this is an anti-Firefox thing. It seems more of a not realising there are other browsers apart from Chromium-based ones thing.