Why not both?
The way Forsaken actually work has been pretty inconsistent. Like the thing with the old lady I mentioned above comes with an asterisk, because the end point of her physical deterioration wasn't rotting away, but entering the 'mindless state', i.e being a zombie. It was previously kind of a given that the Forsaken didn't rot in the same way or that this could be held at bay with various potions and shit, but that the magic keeping them together waned. Hence why they were also super resistant to harm. Now though, they've moved into them requiring more maintenance, which is also a good angle on its own, but contradictory, since we have stuff like Chadwick's party still showing the old kind of Forsaken resilience.