Mozilla is developing an add-on called Go Faster that uses WebCompat data to adjust settings in Firefox for compatibility on poorly tested sites.

https://github.com/mozilla/webcompat-addon

https://wiki.mozilla.org/Compatibility/Go_Faster_Addon/Overr...

https://webcompat.com/

Firefox already ships some UA overrides. You can see the list of active overrides (with links to bug reports explaining each) in Firefox's about:compat page.

It looks like about:compat is the desktop implementation of the Go Faster add-on.

https://hacks.mozilla.org/2019/07/firefox-68-bigints-contras...

Good to see this in action already.