This isn't a question but just sharing this because it threw me off at first, and the only other thread I found about it was locked and the community experts were absolutely clueless about it even after the person shared a picture of it.
If you see a large speech bubble icon on your Nest thermostat's screen, this is just letting you know there is some form of notification or reminder. If you approach your thermostat, the message should display and then you can clear it by interacting with the thermostat itself.
Moderator edit: Subject updated for clarity and findability.
