I'm not sure what the heck is going on with that snake, but single gene pastel definitely isn't it.
That thing is crazy bright, and what's with all the smudging? It looks like it got manhandled by someone with dirty fingers lol. It is an oddball for sure. Breed and breed babies back! (That's basically my answer for everything morph related these days)
Edit: and yes, the fire gene lightens with each shed usually, even when mixed, to a degree. We're not talking about desert ghost color change here, but it definitely gets lighter/brighter.