My driver seat has squeaked during acceleration & braking forces ever since it was delivered. All I can tell is it's coming from within the backrest. Tried removing that plastic cover one time and gave up because it was approaching "This is absolutely going to break something" levels of force. Mobile Service later visited for an unrelated appointment, and wasn't willing to investigate it; just shrugged and suggested it'll go away on its own.
I've put up with it for a couple years now. Maybe we'll get a golden reply from someone explaining the proper removal technique and where the retaining clips(?)/fasteners(?) are located and how they're best dealt with.