Does the smoke alarm in the hotel room flash on and off?

Yes.

According to inquiries on Qijia.com, we learned that the smoke alarm in the hotel room will flash a red light when it is operating normally. It does not flash all the time, but flashes every few seconds, and sometimes it flashes for fifteen seconds. Once, this is the equipment being inspected. When an abnormality is detected, the red light will keep flashing and an alarm will sound to notify the residents.