This post is more of a "heads up" for anyone contemplating buying/using an ASI120MM/MC (the puck-shaped versions, not the "mini" 1¼" version) with an Astroberry for guiding than anything else. As far as I'm aware, there is no fix for the issue described below.
In short, just look at the following gif of my ASI120MM operating in PHD2 on an Astroberry RPi3B+:
It does the same thing with the internal Ekos guider.
That jumping around isn't just a visual artifact, either: the guiding software thinks it's real and tries to compensate.
I have found that extending the exposure length to 2.0, 2.5 or 3.0 seconds tends to diminish the issue. PHD2 seems to be slightly better at handling this phenomenon than the internal Ekos guider, but there's not a lot in it. When using the internal guider, it frequently stops and restarts guiding due to RMS being exceeded.
My ASI120MM has been updated with the ZWO firmware (yes, using the -compatible firmware file, and yes, run from a Windows box with the Windows firmware updater from ASI), so that's not the cause or a solution.
Additionally, in conversation with another astrophotographer, I've been able to confirm that the generic T7 / T7C astrocameras (pinkish with a slim 1¼" profile, pictured below - they outwardly looked to be well designed) available on eBay, Aliexpress and Amazon etc. also suffer from the issue when used on an RPi. However, I haven't experienced the same issue when using it directly from a Linux laptop running Ekos, though I believe others have.