Bad design. Plenty of EVs have their brake pedal apply a mixture of regen and friction braking, with the actual proportions dependent on factors like how quickly you hit the brake (soft braking is entirely regen, slamming the brakes apples almost entirely actual brakes in my experience), or how much charge is in the battery (you can’t safely pump power from regen into a nearly full battery).

Plenty of them also let you control how much passive regen happens when you lift the pedal, with the default on mine at least feeling very similar to the slowing you get when lifting off the gas with an automatic transmission. It’s adjustable from none at all to moderate braking force, and when I turn it up lifting my foot from the gas illuminates my brake lights.