We all know this will happen eventually and some figures will go sooner than others. The discoloration is actually much worse in person.
My collection was on display in a small closet at my parents house. Now that I have moved out I needed to store it. I discovered Lando hadn't faired so well. FWIW the closet had no air return but didn't get any warmer than 80 during the summers. However there was no air flow and its a humid part of the country. If I had to guess it was the lack of air circulation in the closet since some of the figures were sticky as well. The top photo was taken about 2 years ago.
As far as storage goes I am storing my figures in full temperature control in GTzip archival bags with holes punched in them. Instead of using plastic tubs I decided to use shoe boxes which already have holes in them for air flow. The shoe boxes are then stacked in a larger box. I also bought some silica packets and placed them in the boxes hoping to keep moisture down.
This Lando will stay in my collection and be used to populate my playsets and I will have to get a new one for my loose set. I have decided to beater figures should have a place in my collection as well so any more that degrade will go to my vehicles or playsets.