Well, there’s no prediction here really, it’s more separating the green and pink, and making the pink grey. You can tell what’s going on at various substages by just plugging the output from an earlier part of the graph into the base color pin.
For instance, take the output of the power node from red and plug it directly into the material base color, you can see what’s going on.
Also opening the texture in UE, you can view the channels separately and see that red is giving the most output for the color you wanted to change. Hence the power node drawing from there… 