I wonder if it's a white balance thing, as in the setting you'd see on a camera or in a post processing tool.

For instance, consider that "soft" or "warm" light bulbs (say 3000K and below) are common in cozy indoor areas. They cast a much more yellow color of light compared with a daylight bulb or actual daylight, which will look very blue in comparison.

It's like the model detected that the image was people in a living room and it applied a warm white balance to the whole picture because most images of a family in the living room have warm lighting globally.

But since it is a machine and apparently has not yet been explicitly taught that comics generally have bright colors and no strange tints, then it does not adjust accordingly.

I wonder if that is even giving it too much credit. Maybe it's just the deterioration from all the iterations of garbage in, garbage out.