E93 stability issues at high speeds? (110+)

I can only describe this as like the rear end of the car is literally flapping like wind resistance or something is making it wobble in the rear. Is the E93 aero that bad that it makes it shake going more than 80mph? I notice it mainly when I am near a wall of barricades or other cars. I don’t know what is causing it! I added a carbon M4 style spoiler and I am not sure if that would cause the entire rear end to wobble at higher speeds. It’s honestly quite scary when you hit upwards of 130 lol