
Cinnabar Changes Color Due to Light Exposure and Wax!
IRL Cinnabar changes from bright red to dark red to brownish to near black when exposed to sunlight.
People have been split between the original Minecon cinnabar color and the new one. Why not have both? Let cinnabar darken through four stages like copper oxidation and wax it to lock the color you want which is how the Romans preserved their cinnabar walls.
My visualization might not be perfect, but I trust Mojang to nail the colors!