It's a roll bar (rather aesthetic in my opinion). All European Raptors are equipped with it with the electric bed cover.
I'm attaching a photo of my Raptor.
Thanks for the pictures?.
What could be moving in there, the whole part where the white plastic pieces are ?
In my case, I really have the impression that only the center of the seat is "moving." Even when trying to force it with my hand, nothing moves.
I have the same feeling in my Raptor.
In "sport" turns I feel the seat move slightly, but it's impossible to reproduce the slightest movement with my hands.
I also feel it move when going up and down (sliding on the seat).