In the last few (very cold) days, I've had 3 instances where, as I was driving, I got an alert that the trunk was open. When I pulled over, the trunk lid was indeed ajar.
Do you have any ice collecting around the lock, switches, or seams?
Working at a body shop, I've learned that a lot of these odd gremlins boil down to either an obstruction, or lack of lubrication; provided the car was built/repaired correctly