Could it be dried food? Give him a soak and see if it comes off.
Just looks like shedding, perfectly normal
I thought it might be, but I’ve always seen and read that shedding looks like white and flakey dead skin. Can it also look like this?
These are the two rescued Russians I have here that are looking for a new forever home. Take a look at the peeling skin on the one:
View attachment 239284
Yes, that "hat" you see on the one on the right, is a flap of peeling skin!!!
This type of tortoise does a lot of skin peeling, but it helps limit it if you keep them slightly humid/moist.