I actually have some respect for you, so I will not give a snarky reply. Here's my background and indeed, one example:

1. I worked for an LED street lighting technology supply company so I know as someone in the industry what goes wrong.
2. Here's just one of many analyses of the purple lights: https://www.nbcdfw.com/news/local/why-are-there-purple-streetlights-around-fort-worth/3192354/

The guy is mostly correct on the cause, degradation of the phosphor (not phosphate though). But he's wrong in that the degradation doesn't turn the LED itself to UV - that is fixed forever by quantum mechanics factors. See #3 below.

3. ALL white light LEDs start with a UV LED emitter - we do not know how to make LEDs that emit white light themselves. It's a quantum mechanics thing, there is no band gap that gives out pure white light. In other words, the base LED for white light is actually always designed as a UV emitter. That part never changes. (red, green yellow LEDs are different, they give out RGY light from the start, they have no phosphor. Blue LEDs are kind of mutants and close to UV.) If you look at many LED lights you will see that the unlit COB LED looks yellowish. That is because there are two coatings on the LED itself. One is the bottom layer over the LED chip; it is a light emitter that takes in UV and outputs white light; the top coating over it is yellow to filter out any UV that passes through. In the shitty Chinese LEDs, they make them with bad chemistry for the top layer and it degrades because any UV leakage actually destroys the yellow dye compound over time.