I had the same problem after the update to ios 14.2 on my Apple TV 4k and my Homepod speakers. There was no option other than listening to the TV Speakers. Prior to the update, I would go to Settings and choose to change the Audio Output from TV Speakers to Homepod speakers. When I finished watching TV, I put the Apple TV in Sleep mode. When I returned to watch again, the setup had changed back to TV Speakers. After update, there no longer was an option in audio output for the Homepod speakers. In fact, the name of the setting had changed from Audio Output to Default Audio Output, and the only choice was TV Speakers. After a little research, I discovered that in my setup of Home, I had designated the Homepod speakers to "Great Room" and the Apple TV 4K to "Living Room", i.e. they were in the same physical room but were not in the same designated room in Home. When I made them both "Great Room", the problem was fixed. Even better, with the update to ios 14.2, I can make the Homepod speakers the default audio output for the Apple TV 4k. That is, when I put it to sleep and then turn it on again, it's already outputting to my Homepod speakers. That's a nice fix!