Not often, but it does happen enough times that I have Chrome installed as a backup in case something doesn't work. It's usually the in-house websites (for instance, the ones made for tracking timesheets) that break on Firefox. Not all of them break, of course, but if you're required to submit a form via a particular in-house website and it doesn't load on Firefox, then you're kind of forced to have a backup browser at minimum.

It doesn't happen often enough that I would say that using Firefox is problematic, but if you combine that with people's inherent aversion to change, you can start to see why people are so resistant to even trying Firefox. Unfortunately, it ends up being a self-fulfilling prophecy, since the less people use Firefox, the less the web development teams at these companies would be incentivized to make sure their website works on Firefox

My power got shut off one day before December last year. I thought the bills were all being paid cause I received no notice of delinquency. Turns out, my electric company purged my account.

When I tried to make a new account, going through multiple attempts where the only thing that worked right was their shitty captcha (select all motorcycles bullshit), I finally had to call them. Turns out, soon as I switched to a chromium browser, it allowed me to complete the registration.

I told the rep on the phone, a nice lady who was as shocked as I was that Firefox wasn't allowing registration to complete, to convey to their IT team that a) removing the accounts of paying customers is a really awful policy (who logs into their power companies site after setting up auto pay?) and b) that catering to a single line of browser was not bad practice. She said she'd pass it on.

I don't think she passed it on.

Yeah unfortunately, things like Apple Business Manager, ezoffice, and our KVM software refuse to work on non chromium browsers, no matter how many user agent spoofing extensions I install