Ah, you noticed!
That’s intentional. The color zones module is very powerful, but also an easy way to do monochrome, or almost monochrome. And even though I really like a high-contrast BW like this one:
https://discuss.pixls.us/t/my-favorite-train-station/40088/3?u=flech
not dropping the chroma entirely ads a touch of warmt to the photo.
I could also have done something like this, with the idea of keeping a bit of the color on the buildings but getting rid of the two blue lights in the original.