Visit about:compat in your firefox. I find it insane that these exist.
Edit: I’ve learned that this is part of the webcompat system addon developed by Mozilla and other contributors. I see why this is beneficial default behavior, since FF has no chance of getting enough market share to matter more if things are broken.
However, this behavior is too intrusive for my taste. For example this injection: https://hg.mozilla.org/mozilla-central/file/8a4afb4d34f8/browser/extensions/webcompat/injections/js/bug1472075-bankofamerica.com-ua-change.js is basically just to silence annoying user reports.
Also, Every site FF pretends to be a different UA on is artificially reducing FF market share data.
Lol, you do realise that chrome does many more. They were recently discovered to allow extra access to google meet over competitors. So not just creepy, but anticompetitive.
I think a more aggressive approach would be better for sites that dont offer compatibility with Firefox.
Do a pop up that asks the user to help make chsnge. First few users to encounter the site could be asked to see if they could find the contact details to let the site know about the problem. Once that is correct, following users could be asked to message them to let them know its a problem.
Keep upping the volume with bad publicity about their website not following standards and bekgn deficient and they will change.
This is closer to what I would be happy with. Firefox could offer an official compatibility extension for each site.