"waves" on the rear panel

OP, I see your RV is an '06. I had an '05 Cougar and the rear panel had that look as well. Keystone told me that the rear panels are not glued but rather held in place with window trim and surround trim. Basically they are "floating". What I was told is that sun and cold over the year causes the rear panel to expand and contract and after a few years, the panel will warp to a certain extent and the waviness you see is the result. Possibly yours is the same?

I've seen brand new 5ers on the lot with a wavy back panel. A salesman once told me that's common because the back of the unit lacks any kind of significant framework.

Moved from Forum Technical Support

is it delamination from water or just glue giving up as you say?
bumpy