Guns weathering effect P-51D missing

[Callsign_NEW 6]

I’ve noticed something a little odd in the P-51D “Glamorous Glen” official skin while seeing some IL-2 videos. The Gun Weathering effects aren’t present in this specific skin for some reason. That oil (could be gunpowder, not sure) stain that is supposed to be both in the lower and upper portions of the wing are present on every other official skin for this aircraft except for this one, that has them only in the upper part, as shown in the images below. Is it supposed to be like that? Is it because of the invasion stripes? Hope someone who knows the reason behind this answers this

Edited May 27, 2020 by Callsign_NEW