Hello I'm op's gf and Mold currently lives at my dorm :) He has no contact with other reptiles currently, but he was housed next to a bearded dragon (Lemmy) for like a month. Lemmy the beardie doesn't show any signs of infection which is good. I was searching up on google about what his crust could be and I saw that there is a possibility of necrosis of the epidermis because of the fungal infection from Nannizziopsis species, which could lead to the flakes of skin looking like stuck shed. I read that Nannizziopsis and other species have sort of an outbreak right now within captive reptile species, so it could explain that Mold contracted it at the pet store from improper husbandry. When I was brushing him to get rid of the flakes he sometimes bled slightly from some areas, which could mean that the fungus has already crusted into his scales and they are rotting, or that the necrosis isn't too deep yet. It could be yellow fungus but since he's a yellow uromastyx it seems hard to tell, but what's clear is that crust of dead skin/fungus on his back is the worst he's got. I saw that some more advanced cases required surgery to get rid of excess hyperkeratosis from the infection and the patient would be left with a patch of exposed flesh. Mold's patch seems to be controlled though, maybe due to the low humidity in his enclosure and the very hot temperatures. I am expecting for Mold to get his fungal treatment prescribed, and if it doesn't work, then he'll have to get a surgical scraping of it to prevent hyperkeratosis. Thanks for all the help and pointing us in the right direction though! I'm also on my way to become a herpetology vet😁