One of the main factors in EV-carsickness is regenerative braking and how it makes the car feel. Like gas-powered cars, EVs still have two pedals, an accelerator and a brake, but most EVs have settings where you can adjust the regenerative braking that is connected to the accelerator. Letting go completely and abruptly in these heavy-regen modes feels like a rough transition, like going from accelerating to hard braking immediately and without warning. On top of having regenerative brakes that are sensitive and tough to control, EVs are quite a bit torquier than the average gas-equivalent vehicle. Electric motors can typically create lots of torque from a standstill, so there's more abrupt motion when speeding up.