The effective number of bits (ENOB) is only ~8.7. Originally designed to have an ENOB of 9+ bits, but silicon bugs lowered it.
There is also some noise from the Pi Pico power supply which could be a good thing if you're willing to average or filter over a large number of samples.
There is also some noise from the Pi Pico power supply which could be a good thing if you're willing to average or filter over a large number of samples.
More details here: https://pico-adc.markomo.me/