Besides that Handoff does not work.
I have several airplay devices (Sonos) and that used to work good. When I redirect my Music output via airplay to the Sonos on my desk it plays the music.
As soon as I background the Music app the music stops playing on my Sonos. Every 30 seconds I get 1 second of music.
When I foreground the Music app again, the music starts playing again.
Same happens for all of my Sonos devices.
I haven't tried my AppleTV 4 yet.
So there is clearly something wrong with Big Sur
My MacBook Pro 2018 is connected via cable and runs OS 11.01
Hope there will be a fix soon.