This happened to my wife and the issue was either Home or Siri being off in the iCloud settings. On her phone go to settings, tap name at top, tap icloud, make sure Home and Siri toggles are on and I think this may fix the issue.Siri asks my wife "Who's speaking?" just about every day when she tries to play music, turn on/off lights, add something to the shopping list. This is one of my few high tech purchases over the last 28 years of marriage where she wants to throw it out the window! Who's speaking, Mmmm hmmm, no response to repeated questions, etc., etc., etc. These HomePods are spiraling out of control. What happened to my OG HomePods? Apple seems to have dumbed them down over the last 4 years. They used to respond to a whisper. Now, I have to yell at them most of the time. Did Apple turn down some setting on the network side to reduce backend processing, etc.? Something has changed. Does Apple expect users will trust their Apple Car if they can’t keep a HomePod running smoothly? Hey Siri, take me to work. ”Who’s speaking?” “One sec…” “this is taking a bit too long” “Mmm hmm?” And while I‘m on my rant, would it be too much to ask the HomePod team to inject a little “love“ into Siri when I tell her goodnight to turn on my ceiling fan, white noise, and turn off the lights? She replies “Goodnight” but it sounds more like a question.
Also open Home app, tap on home in top left, home settings, tap wife’s name, make sure Recognize My Voice is on in the Siri section just to be safe.