Regenerative braking

[Lily the Pink]

Having had a first test drive in an EV (MG5), I was surprised at the level of regenerative braking available in some circumstances. The car has three settings selectable by the driver (Heavy, Moderate and Light) and certainly Heavy seemed to me to provide a lot more deceleration than engine braking in an ICE vehicle. I am unsure whether the brake lights come on (and if so at what rate of deceleration), or whether it would be advisable to touch the brake pedal to make sure they do.
Does anyone have specific experience as either an EV driver finding yourself nearly shunted by a following driver, or as a driver following an EV finding it suddenly slowing without brake lights showing ?