my reasoning: the actual colors we can see -> the wavelengths that we can extrapolate to -> basically extrapolated wavelengths plus an 'unpure-ness' factor -> not even real wavelengths (ok well king blue and maybe lavender if I'm being generous could be)
And your brainhole specifics - everything gets processed like this (even monitors with subpixels use a lot of this stuff, or even why you can watch 24p movies):
wiki/White%27s_illusion
yea, there's also the afterimage / auto white balance factor
also those are fun optical illusions
mildly unrelated, but have you seen https://en.wikipedia.org/wiki/Caf%C3%A9_wall_illusion and https://www.shadertoy.com/view/4dBfWK
Yes, brains are wild!