Most agoutis tend to grow their hairs out in layers, so they end up with a weird patch of colors between molts. Although with a chinchilla, I would more likely assume it's sun damage, since their hairs shouldn't have any yellow/brown/red in them at all (the gene for chinchilla suppresses that/covers it up with the gray/white and black).
The only way to completely prevent it is to make sure they get no direct sun exposure, which means no corners of the cage/play area allowed to get sun since the rabbit will inevitably decide to lie in the sun at some point.
The amounts they have probably aren't hurting them, so unless you're showing, a little bit of sun does no harm. Just make sure that they ALWAYS have ACCESS to enough shade for them to do a full-body flop in.
I'm not showing but I thought maybe I had been jipped on her being Chinchilla lol! I guess I'm glad to know it's just sun fading. I'll try putting up more shade to see if that helps any.
I thought it would be less brown! My rabbit, fuzzy, is also a chinchilla and he has that kinda frosted look behind his head on his white spot... but not almost completely brown...
Yeah I was kind of worried when I first actually noticed it. I mean, it's so bad that it shows almost perfectly in photos. I wish I would've got better photos but she was being fussy. But you see what I mean right? She's got light brown tips like over her entire body. D=