There are definitely artifacts in the (clipped?) highlights introduced from darktable and not from the demosaicing algorithm itself.
From this PlayRaw I get weird artifacts using the match greens option in demosaicing .
170322_Waterloo_Bridge_37.CR2.xmp (9.9 KB)
Here is possible to observe the darktable’s green bias noise (just demosaicing with amaze and addind 2EV in exposure)
Darktable
Photoflow
Rawtherapee has blue-ish shadow but the noise level is the the same of Photflow
Also looks like Darktable doesn’t round to nearest when exporting to 16/8 bit tiff.