Buzzing noise in rear passenger tire wheel well after car turned off

Hello,

I'm new to the forum and recently just bought my first Volkswagen, a 2019 GTI Rabbit Edition in Cornflower Blue with DSG. It is an awesome car. Recently discovered a strange buzzing noise in the rear passenger wheel well after the car is turned off. It sounds like a small air compressor and the sound stays on for about 3-minutes and stops with a popping sounds, kind of like a safety relief valve. I experience this after driving on my commute home, recently after running the car in the driveway while adding air to the tires. The dealership service department cannot figure it out and I reached out to VW Customer Care and they don't know either. Any help would be much appreciated. I think this is normal, but not encouraging when VW and the dealer have not heard this issue before. Thanks.