There is a red light flashing on the ceiling of some rooms outside. What is that?

Honey, the ceiling is white. Is there a plastic hole around it? If so, please 1 rest assured. Because that's a smoke alarm. It's used to put out fires. In other words, if the house is on fire, there will be a lot of smoke. When the smoke concentration is too high, it will trigger an alarm, and then the fire control system will know which floor and which room has a fire, which is conducive to quickly locating the fire source and ensuring the safety of the house. It is also a lot of tall buildings.