I've been doing more measurements after some discussions on discord after publishing the blog post. There's definitely some kind of interleaving going on, but even when applying a square wave at the input (that gets displayed perfectly fine on the scope CRT) there is a lot of noise on the ADC input that can't be explained away. I will update the blog post tonight after doing more measurements.
Some people have also suggested deliberate addition of a pseudo-random signal that gets removed after sampling to counteract some CCD issues. But I don't know how that would work either.
Some people have also suggested deliberate addition of a pseudo-random signal that gets removed after sampling to counteract some CCD issues. But I don't know how that would work either.