I haven't hit any real problems with Firefox. Maybe it's the sites I visit. Mostly news, shopping, and tech stuff.
The only real exception I can think of is that Google Meet's audio quality has recently been worse under Firefox than under Safari's. My guess is that the issue is on Google's end (since Firefox used to be fine), or that maybe Safari has access to some special microphone APIs.
Since you mentioned Safari, I assume that you're on MacOS where Firefox and other alternative browsers are effectively hindered at the framework/API level there, as such browsers have problems there that don't occur Linux or Windows.
For example, the audio in FF outside of Apple sounds real clear and overall great in my experience.
The only real exception I can think of is that Google Meet's audio quality has recently been worse under Firefox than under Safari's. My guess is that the issue is on Google's end (since Firefox used to be fine), or that maybe Safari has access to some special microphone APIs.