That EU regulation's § 5.2.22.3 he mentions, read "electric regenerative braking systems, which produce a retarding force upon release of the throttle pedal, shall not generate a signal". But it now seems to be modified into "activation of part of the service braking system by ‘selective braking’ or by functions whose primary intention is not to decelerate the vehicle (e.g. slight actuation of the friction brakes to clean the discs) shall not generate a signal". Which doesn't look too strange to me (yes indeed, before, the wording was strange and even dangerous).
Anyhow, I don't recognise that Hyundai's behaviour in my car (it only has one-pedal drive available). I don't know exactly how it works (I tend to think software-determined decelleration-based), but if I decelerate gently, my brake lights don't illuminate. And if I let go my acceleration pedal more eagerly (not necessarily fully released), they do. Once I'm completely stopped, they also illuminate (automatically). So I don't think there's a big difference with "normal" ICE cars...
And by the way : recall these Huyndai's ? Nowadays, there's also something called "Over The Air" (software) updates. Should all be fixable in 1 software update...