I just read an interesting article posted by red Bull on the rules of parc ferme pretty interesting actually. The cars are basically owned by the fia while in parc ferme or parc ferme conditions. Seems the fia scrutinizes the cars in depth and at random once there, and withholds the right to keep the car for several hours before/after a session. I assume this is why max was fined. Actually surprised vettel wasn't fined a few years back. I recall him touching hamiltons tires at the minimum a few years ago in parc ferme. But I guess that wasn't a part being scrutinized.
Whole article can be found here:
https://www.redbull.com/ke-en/redbul...-to-parc-ferme