You aren’t regaining 100% of the kinetic energy so a significant part has to be lost somewhere else. Realistically regenerative braking is recouping energy that

You aren’t regaining 100% of the kinetic energy so a significant part has to be lost somewhere else. Realistically regenerative braking is recouping energy that would be lost as heat when the friction brakes act on the wheels. However it would not stop a vehicle on a zero friction surface, as a simple example, so no it doesn’t take away from the friction heat losses on the road.