This came up on another thread a couple days ago. Cats puking when in Machs.
I stand by my hypothesis that its the magnetic field produced by the battery.
Personally I would blame most of it on regen braking. I do not like the feel of the more aggressive regen so I do not use those settings. I imagine if I were a passenger in an EV with aggressive regen it would bother me. Just my personal experience.
Conspiracy theory if I ever heard one. No science here. It's just your heavy foot and the great torque. You go on a date, and when you get home she says: "Sorry, I have a headache". Blame it on the car.