Same thing happens if you ask “what surface is the table on” or “what country is this image in”. It’s layers I can add to the mental state, but if they’re not important they’re just not there.
I’d say the closest thing to what I was “seeing” before the color question is something like a wireframe, or maybe the gray color of a Blender model without colors/textures applied. Grey in the sense that you don’t really notice it’s grey, you just understand the grey color means color is absent.