Edit2: there shouldn’t be anything fundamentally different with the brakes compared to an ICE, particularly on an older leaf!
There isn't. Regenerative braking doesn't actually have anything to do with the brakes. It uses the cars momentum to reverse the electric motor, which slows the car down and charges the battery. If you brake a bit harder the computer then tells the brake system to activate the calipers on the discs just like any other car. I seemingly know more than many "mechanics" about the mechanical workings of a modern car and I don't even really like cars than much.