Looks like he’s been immersed in water for a long time, or maybe scrubbed really hard. I had this happen to a very old Gargoylingus when I washed the dust off of it, and the eggshell detail just started peeling off! In my case, I suspect the previous owner cleaned the piece with a solvent, like glass cleaner or furniture polish, that dissolved the protective clearcoat over the paint.
Forever seeking: Blackwatch the raffle Old Warrior, Jennifer Miller's pieces, and GB Baby unis!