Looking back, I feel that CSP does not achieve pigment blending…
It’s hard to imagine that real pigments will maintain brightness during mixing.
And it has an option to adjust brightness, which sounds like SubAdd：
Perhaps they just found an algorithm that blends yellow and blue to create green, and then brightened up the middle (like Krita’s geometric mean and parallel, which can also create green)
One characteristic of pigment mixing is that most dark and bright colors have a high saturation in the middle when mixed:
I guessed at first that it was geometric mean. But if it is called ‘visual’ and the brightness remains unchanged, it is highly likely to be oklch (if its red and green colors can blend into a bright yellow)