Strange streaks from Deep Sky Stacker

[Bugdozer]

This is a section of a recent picture with 60 subs of 30 seconds each, that was stacked along with flats, darks and bias frames as normal in Deep Sky Stacker. I have exaggerated the levels to make the effect more visible:

You can see there are a lot of strange black streaks across the image. They're everywhere in it and on the black sky background they aren't too much of a problem because it's darkened down, but where there's a brighter area such as across nebulosity etc they become more noticeable. There's nothing corresponding to them in any of the individual exposures that I can see. Can anyone advise what might be causing this artefact and how it might be eliminated?

[ONIKKINEN]

Looks like walking noise, which is a capture issue and goes away with sufficient dithering.

OSC cameras usually have a fixed bias/dark pattern of some kind that usually is seen in the form of horizontal banding. If we dont dither we stack this pattern on top of itself and reinforce this to a point where it can be seen in a stacked and stretched image like i think has happened here. Dithering by a good 10+ pixels every now and then mixes this pattern and it will get either evened out by stacking or just removed by rejection algorithms.