When I activate the "EhiSiri on Studio Display" option and then put the Mac to sleep, the monitor turns off, but the Mac Studio remains active (the fans keep spinning). This does not happen if I activate the "Hey Siri on headphones" option. I noticed that the corespeechd process is preventing the stop. On my MacBook Pro 14, on the other hand, if I activate "Ehi Siri" (on the internal monitor) the problem does not arise: the corespeech process is active, but it does not prevent the stop.
I checked using the Activity Monitor as well