Also have these issues. Since about July, 2024 - prior to to current software updates. I had expected one of the releases since, to fix this issue.
One of the original HomePods (bought 2 to stereo pair 5 years ago). Tried restarts, resets, different WIFI settings - many times. Issue remains. I have taken the speaker into Apple...they just looked at it, literally.. and read this article. It was like they already knew this was an issue. (but told me they had not had anyone come in with the issue/ speaker. I was given an option to replace it, with a minor discount - still costing me $400 plus AUD...AND the latest version only, that is NOT compatible with with the other HomePod that still works as you cannot stereo pair a Gen 1 with a Gen 2!
So they then handed me some paperwork to go onto the ACCC website, and log a "complaint" with the Australian govt body, on fair trading.. If this ended up being a positive outcome...it would ask Apple to replace with another GEN 1...so I can then Stereo Pair - but again...at a COST to myself, of a few hundred dollars.
So I have cancelled my Apple Music subscription, as this issue is obviously widespread…and Apple have not done anything about it. And after 20 years of Apple ….I am noticing a distinct lack of care.. all around, and it feels the “golden age” is now over, as its now all about the $$$ profit.