Not sure if it is nouveau related…probably…but all
graphic images inside Scribus 1.3.3.14 are totally scrambled using 11.3.
Possibly because I have no problems with graphic images in Scribus. Are they EPS? If not, try using EPS images. If the EPS images are scrambled, then it is not a Scribus problem. If they are not, it is possible that the formats you are using are not well handled by Scribus.