Wonder if you did a VCDS scan whether you would see anything. Something the earlier versions that Kessy don't do. My passenger side goes into sleep mode related the the battery voltage if the car isn't used. The electric tailgate ditto. Pull handle then it sorts itself out. Not often.The manual says that KESSY deactivates when it detects too much activity on the handle (e.g. a branch hitting the handle in the wind).
For example, at a car wash, water can open and close my car. So I suspect that the same happens during rain/snow, but due to the lack of a key near the car, the car does not open, but the activity on the handle is registered - this causes its deactivation.