Yes anything GPU related other than CUDA is a shit show on Linux desktop. Another issue is that YT loves to use AV1 if they know you're on desktop. Almost all desktop users have a CPU powerful enough to software decode it in realtime, but if you're on a prebuilt PC you'll definitely notice the fans kick in
I can't speak for Firefox, but Google Chrome (and presumably anything Chromium-based) has working hardware-accelerated video on AMD and Intel GPUs.
It does admittedly take some effort to set up; I assume Google is hesitant to enable it by default because of issues with Nvidia GPUs. But when configured, it works and has for years.
