Hi there, it looks suspicious but just to rule out it being something harmless like food, old shed, poo or dirt can you give Crush a warm
bath + see if it comes off with gentle scrub from a toothbrush ? If it doesn't, it may be fungal. Then you'll want to get her seen by an experienced reptile vet. They can do a skin scrape to have it analyzed to see exactly what it is. Some fungal infections [ yellow fungus ] can be dangerous and even deadly, so you'd want to do so ASAP. Hopefully it's not too serious .