Here's how you can fix this all at once: https://old.reddit.com/r/firefox/comments/g3tyfu/how_to_swit...
Google is intentionally breaking support for Firefox on their websites. Other just don't care and support monopolies.
Compared to her I rarely use my phone for browsing, I do not feel as impacted.
You can't do video calls with Teams in firefox for a really clear and obvious example, but I encounter breakages quite often and have to switch back to Chrome.
Safari suffers the same, but I get the impression people are testing safari more than Chrome.. but I hear so many complaints on hackernews about safari, I suspect at some point Chrome penetration will finally dislodge Safari on MacOS... or if MacOS market share goes down: then it's over and we have a total monopoly.
Even Reddit on Firefox PC crashes occasionally (the whole site turns white while browsing). Reddit on FF on Android is barely browsable.