Kudos to Leica for even offering a monochrome camera. But if you’re gonna do it, do it right, and that applies to anything in life.
Back in May of 2015 with the Leica M Monochrom Typ 246, I reported on a “black dots on white spots” digital artifact problem (sometimes the reverse, white on black).
Whether it was fixed in the M246 is unknown to me, since I never had another camera to verify during the ensuing years. But it seems doubtful, given its re-emergence in the 40-megapixel Leica M10 Monochrom as shown here—whatever engineering is involved, it looks like the same bad juju.
Here in 2020 (5.5 years later), the 40-megapixel Leica M10 Monochrom suffers from a similar “white spots on black dots” issue of exactly the same nature and just as unacceptable—all irreversibly baked-into your raw DNG files.
If you’re a glutton for punishment, the M10m or M10-R will also bake-in irreversible color shading/vignetting modifications to the raw file*, using the wrong lens profile.
I’m not surprised at either problem, because aside from a few welcome changes with Live View, Leica has done very little to improve the firmware in the Leica M10-R and Leica M10 Monochrom, including failing to fix camera crashes (total lockups) which I experienced at least a dozen times in my one-week trip over XMAS—same bad software engineering as back in 2015. But if they just offered a designer ostrich-skin version of the M10m, then I could look the other way.
* "Auto" lens correction bug when using a non-coded lens or a coded lens while forgetting to go off manual lens selection—I enjoyed this treat as well when using the Zeiss ZM 35mm f/1.4 Distagon.