Please help. New redeye charger makes soft “clunk” noise every time car gets started.

Before I take it to dealership (don’t really want to do it to a new car), maybe someone can help identifying what makes the noise. My 2017 cat didn’t have this issue. It’s a soft clunk, coming from behind me, seemingly on the left side. Most of the time I hear it right after I start the car, but sometimes it happens later. Only happens once per car start. Nothing is loose in the car, I checked, plus most of the time it happens when car is motionless. Any idea, please?