Why did I turn off the light and it kept flashing? The south wind has been blowing recently, and the room is very humid. Is this related to this factor? )

According to what you said, there are two possibilities. One: the switch wire is connected to the neutral wire (ground wire). Two: the position (or line) of the switch is extremely wet. Both of these phenomena will lead to the normal brightness (standard brightness) of the opened switch. When the switch is off, there will be a flash and a faint light. Check all connection points and rebind. Check the terminal phase of the switch to solve the above fault.