Quattro’s 2-pixel noise artifact finally gets some attention at dpreview.
Samples from the OP: https://www.dpreview.com/forums/post/60240987
I addressed this issue more than 3 years ago already in that forum.
I called it „ants“, „flecks“, „spots“ or „2-pixel noise“
Here from 2014:
August 2016 (noise reduction can't remove it)
It seems that only forum member tagscuderia recognized this error also and mentioned it repeatedly.
Just like now again:
„As a dp0 owner let me say that the 2-pixel crawl artefact was evident from day one and has been touched upon on here... but seemingly only Maceo and myself could see it?! We did however both independently report it to SIGMA with examples“
Probably he won't be heard again.