see also:
https://www.thurrott.com/forums/microsoft/windows/thread/you...
Which seems to be claiming the software fallback has been suddenly yanked, temporarily breaking YouTube which fixed it by serving VP9 instead but maybe AV1 hardware decode is still working?
What you see is that they implement different features with Google obviously wanting the browser to be a full blown OS. So they added things like MIDI support and web pages being able to access the battery.
The problem with many of those features is that they have been shown by researchers to either (a) be insecure or (b) allow web pages to uniquely fingerprint your device. This is obviously an anathema to everything Apple believes in.
[1] https://caniuse.com/?compare=chrome+121,edge+118,safari+17.2...