Their AVC encoding is pretty bad, yes. Simple solution there if you have an AMD card: Don't use it.
If you're streaming use x264, it'll look better than either AMD or Nvidia hardware encoding at streaming bitrates. If you're recording locally use HEVC or AV1 which AMD does much better with than AVC.
What's the actual alternative they want here? That users look up download URLs on other devices and download their browser of choice via command line using ~~cURL~~ Invoke-WebRequest? That ISPs provide browser installers on USB sticks?
Also, it's not like MS is cornering the market on browser share here. Even with this "unfair advantage" they've only scraped together a 5% slice of browser usage.