Not the skull, but probably the scalp. Our scalp is made up of skin, fat, and muscle. When you press a rigid object against it for hours every day, that soft tissue temporarily compresses. It happens to my kid who wears headphones for gaming. It's the same mechanism that leaves red marks on your nose after wearing glasses, or grooves on your ankles after wearing tight socks. Wash your hair, give up on the headphones, and it'll return to normal.
The QC2 are about half the weight of the AirPods Max, and apparently the mesh in the AirPods Max band sags, and allows the metal bars to "dig in" to your scalp. Enough to cause irritation, but 400 or 500 grams resting on your head can't mess with an adult, developed skull.
It literally gives me a headache after more than an hour of wearing it. This never happens with may AKG that has a very utilitarian and simple headband—a flat piece of plastic. It’s not pretty but I can wear AKG for a whole day and enjoy every minute of it while I’m phisically sick after an hour of AirPods Pro.
You're joking, right? There are many high quality competitors in that price range. I'm holding a pair (Sennheiser HDB 630). They are significantly lighter weight, better comfort and sound quality.
You shouldn't need a medical background to know that having something press on a spot for a couple of hours will leave a depression in your skin.
You have probably fallen asleep on something patterned or folded and have it leave an impression on your skin before: This is no different.
Other places it happens: Watches that are slightly too tight or have ridden up an arm. Glasses arms pressing against your temple or behind the ear. Tight socks after a day wearing them.
It's not a medical problem. It's just general physics.
What he's saying though is that the original poster is vastly overstating the effect the headphone had on his head. There was no dent in his skull, just skin deformation that happens with literally every headphone.
Another poster here - I can confirm, have the same thing. I don’t worry too much about it though, I assume it will fade if I ever switch to other headphones.