All ball pythons brown out to some degree or another with age. Newly fresh hatchlings (even the most "normal" of them) have a lot of yellow and orange coloration that quickly browns out over time. The yellow can stick around longer, and some may never lose it entirely...but most older ball pythons have a lot less of it than younger ones. I have one big normal male...no idea how old he is because he's an adopted rescue....he's huge for a male, so is probably many years old, at least.....he almost looks axanthic because all his yellow has faded away...but he's just a big ol' lovable normal.