Another thing that is turning purple is the prose: "The mystery of the purple lights appears to be both more mundane and more worrisome than anyone has realize

Another thing that is turning purple is the prose: "The mystery of the purple lights appears to be both more mundane and more worrisome than anyone has realized — a mood-indigo check-engine light on the entire infrastructure of modernity. When LED streetlights start changing color for no apparent reason, it's a visual cue that we might need to rethink, just a bit, how we build the future." Or maybe you're desperately stretching for a hook for a story about a quirk of LEDs.