I used Ubuntu Budgie (up to 20.10) for years with Firefox and the only problem I had with it was its refusal to play BBC News videos (Youtube etc were fine). Now a bug in the installer Ubiquity has made it impossible for me to continue with Ubuntu 21.04. I haven’t used Fedora for years so I am effectively a Fedora newbie. I have a 3.4GHz x2 processor and 4GB memory of which only 3.2GB can be used because of a BIOS bug.
I am very impressed with Fedora-34 + Gnome-40 and would be very happy to stick with it now - except that Firefox keeps hanging. Chromium is fine. Not sure whether it’s worth posting a message on the Firefox forum as well.