Weird bug with Processing lights

I’ve been doing some experiments with marching cubes lately, but it was really hard to look at the image as 3d because there were no shadows or lighting. I tried using processing’s built in lights, but I got this weird issue where the lights aren’t grayscale and also shift colors? Here is the bug:

It’s faint, but the lights are blue and I really don’t know what’s going on. Is there any explanation for this?