I would suspect that it is the weight of the vehicle that is the primary driver there. There is some additional negative effects of the vehicle being taller (in

I would suspect that it is the weight of the vehicle that is the primary driver there. There is some additional negative effects of the vehicle being taller (increasing roll), but that is probably mostly mitigated by the battery pack pulling down the (vertical) center of mass. But certainly the aerodynamics creating less down-force would play some role.