They record only after the trigger word. It's the same as Android phones and iPhones that have "OK Google" or "Hey Siri" enabled. In practice we know that trig

They record only after the trigger word. It's the same as Android phones and iPhones that have "OK Google" or "Hey Siri" enabled. In practice we know that trigger words for all these devices occasionally misfire (There was also an issue with one type of google home device a while ago which was shipped with a faulty physical button that caused it to be turned on at intervals as if the user had pressed the physical button to start speaking).