Yeah. Most recently it was a shitty site that looked like it had been built in 2000 and I had to use to pay an EMS bill: services.webillems.com

Tried several times on Firefox and it wouldn’t let me proceed with the payment. It kind of acted like it had. But when I called them to confirm they said it never went through. Tried multiple times with the same results. So I then tried on Chrome and it went through first time.

There’s have been others too. But like I said before, it’s rare. But annoying.

It’s down to these sites using stale, poorly-written legacy code and/or never being upgraded.