Mystery false alarm

I have a ring doorbell with a powered supply and a few door contact sensors and motion sensors. Last night at 4.20am the alarm activated for no apparent reason and when I investigated I found no cause. The ring app event log showed “Front door “ had alarmed but it’s not clear whether it was the ring doorbell or the “Front door “ contact sensor as they have the same name (I have renamed one). There’s a paper clip icon next to the event. The doorbell is outside and it was -1C but the door contact sensor is inside where it’s warm. I don’t know how to find the cause and prevent recurrence. Any ideas please