SOLVED: How can I reduce ADC jitter

[Demon]

...ansel does not override wpu , what you claim makes zero sense ...s

Got that info here, at the bottom:

https://developerhelp.microchip.com/...ly/digital-io/

The pull-up will be disabled automatically when either TRIS is set to an output or the pin is set as an analog input. These changes to TRIS and ANSEL will override WPU settings

Anyways, I'm setting the WPU only for the unused pins now (even analog), playing it safe despite that quote above.

...your power supply must be very noisy or the pots are complete crap [possibly microphonic] to get such poor results

The TPS56637 seems very stable, especially since I have nothing on that one. The LCD and LED strip are on a separate TPS56637.

What do you mean by microphonic? Are you talking about the taper? Mine are linear, like Bourns B: