Audio Airplay 2 on stereo HomePods 2 via AppleTV 4K has drop outs and is unreliable

Audio Airplay 2 from an iPad Pro 10.5" or iPad 9th gen to 2 HomePods 2 with AppleTV 4K has been working unreliably for me for a few weeks now. It's slightly better without AppleTV. I can't understand why the AppleTV is necessarily involved in audio streaming. There are no diagnostic options from Apple technology to track down the problem. The WiFi is excellent, everything works perfectly, only Airplay audio causes problems.