RVs suffer a lot of twisting action when traveling down the highways or leveling at a campsite, so it's not uncommon for an entry door frame to shift a enough to create this sort of problem. It could be either the door sagging or the frame going out of square, and often difficult to see which one and where the interference actually is. Sometimes it helps to put a powder or paste on the door frame so that you can see where the door rubs. Talc, hand cream, anything you can wipe or wash away afterwards. A real thin tape might work too.
Once you know the source of the problem, you can try to figure out a fix. It may be possible to jack up the door or the frame a bit and shift it back enough to solve the issue, but that can go wrong too, damaging it even further. I've seen some coaches where it was necessary to jack up the body under the door and weld in a gusset to hold it in place. That takes some skill & tools that few RVers have, and not many RV shops either. Might need an RV body repair shop for that.