This may have happened to you. You asked Google Assistant to switch off the lights for the evening so you can sleep. Google Home then answers back, probably a bit louder than you'd like, to confirm that it's turning off the lights... as it, well, turns off the lights. It seems kind of redundant and counterintuitive, doesn't it? Google has heard you and it's started rolling out a new feature. Assistant will no longer verbally confirm that it's turning off lights. Google Home will chime to let you know that it's processed your request, as long as it's in the same room as the lights. And it doesn't just work for turning off lights, it'll work for all light-related actions like dimming, changing colors, etc. It'll also work for switches and plugs identified as lights in Assistant's settings. Smart lights will reportedly be getting the new, quieter confirmation in the coming weeks. And this feature will supposedly work for all Assistant-powered speakers and displays, as long as the device is grouped in the same room in your account.
Source: Android Police