I use Firefox but there are web apps that just plain do not test on it. Office 365 is one of those and Word is basically non functional...more than normal.
I can't even log in to Lemmy properly on FireFox for mobile. And many drop down type selection boxes across tons of websites also do not work on either mobile or desktop versions of FireFox; this one irritates me most, because this was an issue years ago when I first was using it before Chrome existed and one of the reasons I originally switched to Chrome over FF at that time. It's been over 10 years and still hasn't been fixed.
For me it's the opposite. There's a few sites that have a lot of problems with chrome but work all fine with Firefox. But then these pages are also a good decade old