HomePod 2 is replying on non asked questions and is playing random music by itself (also in the middle of the night)

Since the last update to version 18 (end October/beginning November) one of my two HomePods seems to have its own live. It started replying all by itself on questions never asked out of the blue. "Found this on the web for you", "mmm mmm" etc. Also it starts playing random music by itself without any reason which is anoying since the two are in stereo par used to my AppleTV which then pauses. I extended the touch time, checked if it was replying only to Hey Siri but no luck. I unpaired the stereo and placed the malfunctioning HomePod in another room. No luck also here it is talking to itself and waking me up in the middle of the night with loud playing music. It is only in one Homepod2, the other one is responding file as expected. Contacted Apple support several times and cases were created but their advice was to disconnect it but that is a weird solution for a device of several hundreds of euro's.! Any one else was able to solve the issue or reported a case with Apple?

[Edited by Moderator]