Earlier quoted context omitted.
In theory no, depends on how it’s done. It’s mostly a concrete ceiling with Bitumen and another polyethylene based layer on top normally, requires renewal every 30-50 years but it will stay tight if done right, at least it’s not much worse than a tiled roof.
Is it better in some other way than an angled tile roof? I suppose you get more interior room at the same heights at least. Where I'm from heavy snow kinda rules out flat roofs so I'm unfamiliar with the reasons you'd want them.
That is the primary benefit of a flat roof, but it is only a tiny number of buildings that are like this. The vast majority of buildings do not allow roof access. Still I encourage it.