Does this happen in high- or low-speed corners? Long turns or short? Tight corners only? Does it happen at a certain speed? S mode only? Does it happen once when cornering or multiple times?
Where does it tap you? Near your neck, small of your back, lower down? Is it dead center, to one side, both sides, alternate with direction of turn. How forceful is it -- is it a tap like a top on your shoulder, is a thump like moving luggage, or a kick like it hurts. Is it constant pressure like it pushes on you through the corner, does it tap once and disappear, or is like knocking on a door?
During aggressive cornering, does it happening during breaking into or accelerating out of a corner? Or does it do it regardless of pedal input?