Now I have not personally experienced the sag as I have not stood mine up however several have posted on multiple forums the sagging with two reports I read regarding permanent creases (fog at the crease). Those were reported last August/Sept.Used the MOPAR bag for months and never got this “sag” that you’re all talking about. Mine’s a 2dr, if that’s a factor.
Keep in mind that a short time in the hot sun, after reinstalling windows, is going to sort out any sag/bend.
Again the 2 doors have no choice, however I would also assume this is more of an issue in the much warmer southern climates.