Visited on November 27 and did a short charge with M-CHARGE RFID, no issue.
The chargers are among the first parking spaces behind the building on the left when entering the Migros parking.
Parking seems to be free. I found just one sign "Migros Kunden max 1Std", at the complete opposite end of the parking. There's nothing written in the area where the chargers are found.
There are manually operated gates at the entrance and exit that are presumably closed when the store closes.
The charging spots are some of the farthest parking spaces from the shop entrance, so this should limit ICEing risks.
Unfortunately, like many chargers placed near the parking entrance, reversing into one of the first spots could be risky given the speed at which people take the first turn.