So, small stuff. Maybe Copilot isn't working because of ublock, though.
I continue to use Firefox because I know when to suspect a website problem might be the browser, but she doesn't have the ability to analyze a situation like this. I have this conundrum with other family members that I support. I want them to use Firefox, but I hate to have them run into an issue because of the browser I recommended.
IIRC, there was also a time when Netflix did not support its highest streaming quality on Firefox. I'm not sure if that's still the case since I also ended my Netflix subscription.
Otherwise I cannot think of any major site which is not supported on Firefox. Outside my employer's fragile intranet, I can't think of any sites which do not support Firefox.
One crap product forcing me to use another crap product! ;)