ws2812 / neopixel timing appears wrong

[gpshead]

https://dubinko.info/blog/2021/09/raspberry-pi-neopixel-code-wrong/ summarizes it nicely.

Your timings appear skewed. They may work in practice but appear to be awkward. Confirming with a scope seems worthwhile.

It's worth updating the PIO code on https://www.raspberrypi.com/news/neopixel-dithering-with-pico/ and in https://github.com/raspberrypi/pico-micropython-examples/blob/master/pio/pio_ws2812.py as well if fixing this as they've no doubt been pretty widely copied by now.