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.
All web browsers have semi hidden pages like this for all sorts of purposes. Its not really intended to be secret, its just not stuff worth even adding to a file menu. Some of the about: pages in firefox are in some submenus, some on settings, but def not all. Tho you’ll fimd them mentioned and linked in support guides.
If anything, the ability to access these is better than them being blocked…