I mean, often, yep. The real reason why they are unhappy with you having an unsupported browser is simply that it's much harder to reason about or enforce policies across bespoke environments. And in an enterprise of a sufficient scale, the probability that one of your employees is making a mistake today is basically 1. Someone is installing an infostealer browser extension, someone is typing in their password on a phishing site, etc. So, you really want to keep browsers on a tight leash and have robust monitoring and reporting around that.

Yeah, it sucks. But you're getting paid, among other things, to put up with some amount of corporate suckiness.

"The real reason why they are unhappy with you having an unsupported browser"

I tend to encourage Firefox over Cr flavoured browsers because FF (for me) are the absolute last to dive in with fads and will boneheadedly argue against useful stuff until the cows come home ... Web Serial springs to mind (which should finally be rocking up real soon now).

Oh and they are not sponsored by Google errm ... 8)

I'm old enough to remember having to use telnet to access the www (when it finally rocked up and looked rather like Gopher and WAIS) (via a X.25 PAD) and I have seen the word "unsupported" bandied around way too often since to basically mean "walled garden".

I think that when you end up using the term "unsupported browser" you have lost any possible argument based on reason or common decency.