I use firefox for everything. The only site I know that doesn’t work is an internal app at my work that was written in FileMaker pro. I just use Edge/Safari for that one.

I use Firefox as a daily driver. And I never encounter these sites. Perhaps we are not surfin on the same pages? Do you have a list of these pages?

I very occasionally run into these, and keep Chrome as a backup browser. I suspect it's as often to do with adblocking though - I have no content blockers on Chrome.

Firefox performs way better and is a more pleasant experience. (This is a fair comparison because my ad-laden Chrome experience is internet as Google intends!)

Is your firefox rendering google maps the same sharp (vectorized) as in chromium? In my firefox it seems not so sharp and rasterized (tiles?), but might be related to some privacy plugins/settings I'm using.

I didn't compare or realize that. So if you are right and most probably you are, I suppose I am not that interested in that sharpness.

Such as? Everything I care about works fine. I've no idea what people are referring to when they say sites don't.

I have had a couple of banking websites, I want to say wellsfargo corporate card login in, as well as video conference sites.

If a website doesn’t work in Firefox (due to a bug in Firefox or the website or because the website blocks Firefox), please file a bug report on https://webcompat.com/

Mozilla developers will then try to reach out to the website’s owners, add a fix or workaround in Firefox, or (as a last resort) spoof Chrome’s User-Agent string to bypass the website’s Firefox block.

In some sense, doesn't the existence of that site kind of strongly indicate that the GP's point is correct. That there are spotty incompatibilities?

Yes, but incompatibilities can’t be fixed if they’re not reported.

Firefox is my daily driver on all my computers and smartphones. There are some hiccups, often with obscure websites and airlines. Most of them better be avoided anyways. However, Slack and Microsoft Teams don't function properly in Firefox.