This isn’t strictly correct.
Colors can be defined by a numerical representation, called a hex code. The glowforge does operations in order starting with the lowest hex code to the highest.
Black is hex code 000000, so it goes first. Pure white is hex FFFFFF, which is the highest, so it would go last. (if it is done at all, I suspect GF might auto ignore white strokes, but have never tried it).
So a pure blue is 0000FF, and a pure red is FF0000, therefore blue has a lower hex value and would come first. It’s no darker or lighter than pure red, it just has a lower hex value.
Custom color palettes that keep that in mind can be really helpful, because really who can memorize all the hex codes? I built a custom palette generator if you want to go all in and make one, but there are simple links in there to just download one if you don’t want to make your own.