Originally Posted by
tarheelnj
It's from people scratching the window trying to get the attention of the jet bridge driver who's looking at his phone and doesn't realize that the plane has arrived.
That's why the inside window is. Also why there's dents on the door by the FA's seats.
The outside window is scratched up from the canopy at a jetbridge that rests on the plane. I know that places like CLE (or at least it did) fit fairly flush, some outstations that use the little ramp, there's a much larger gap. (You can see the same thing on planes that board from door 2L, there's much less inward slope.)