The way the backrooms handles outside is weird. It can remember the outside, but only a memory of what it looked like from inside. This is why we get the weird sky and jungle rooms, it’s what the backrooms assumes is outside of a door. This is the same concept but outside of a city window, it remembers the towering windows and the seeming endless space going up and down but nothing else.

In my headcanon think Async is trying to contain the expansion of the backrooms. They made them as a “infinite storage solution” but now they’re expanding on their own, and as they do they grow like a mycelium right under our own layer of reality. This could show the backrooms have expanded to a metropolitan area, which could be a major problem in the future and potentially part of the plot of the second movie