I had the same problem, AirPlay no longer working to my reciever (Yamaha RX-A850). At first I believed it had to do with my iPhone 11 Pro update to 14.6, and Mac mini M1 update to 11.4.
But now I know it had nothing to do with that. I tried to connect to AirPlay from my iPad (14.4.2) and my old iPhone 6S (13.5.1) and the result was exactly the same: reciever is missing in the reciever/TV list.
I have tried on different units to turn off/on "Handoff" and "HomePod". And tried to change between "Never", "Ask" and "Automatic" for the AirPlay request settings. Nothing works, this is at least in my case obviously not an Apple issue, this must be the recievers fault.
Of course I have rebooted everything (several times). I can connect to my Apple TV through AirPlay and then let the music stream to the reciever, so it's no problem running the protocol on my WiFi network.
I googled and found some other with similar Yamaha reciever and AirPlay problems, but not that many. The reciever is not old, but everything can of course broke at anytime.
Hope you guys will get a better answer to this issue than I got.