Gluing paper to PLA objects
The problem is probably the UHU glue having not had the time to cure through and interacting with either the PLA, the moisture in the garage, or the brick-paper's covering foil. Many of the metal-tube UHU glues - like &quot;UHU Hart&quot; - are resin-based and contain solvents that can interact with some polymers like the coating of the brick paper. Curing times can be up to 48 hours to cure.
I have had a very good experience with very basic water-resistant Wood Glue to both smooth over 3D-prints as well as attach layers of wood or paper to it. Most wood glues are made with a chemical that is the same or similar enough to those in Gluestick (usually PVA, sometimes PVP). These usually don't react with the fibers and surface of the NOCH-brand brick paper I know.
After having the glue dry thoroughly - for Express type wood glues that is about 2 hours - there is little to no chance that the two interact badly in the garage.