I switched to FireFox like 8 years ago, but to be completely honest there are maybe 2-3 very important sites that straight up do not work for me at all with FireFox. Like, completely unusable, not just weird graphical issues.

Such as?

accuweather.com was the biggest one, though it looks like they fixed it sometime in the last month.

I used accuweather.com in Firefox a bunch a decade ago. Did not have problems.