Using Affinity Photo 1.9.1.979; camera Nikon D7200; shooting NEF+JPG; working with well-exposed images that display normally in AP 1.7 and AP 1.8.5 (They also behave normally in ACDSee Ultimate, DxO Photolab 4, and Nikon NX Studio).
When these same .NEF files are opened in AP 1.9.1 the image appears washed out and the histogram is skewed to the left. The .JPGs of the same images display correctly.
The screenshots of test images below are "as opened" with no adjustments, and clearly show the difference between for example ACDSee (top) vs Affinity Photo (bottom).
The same problem affects older .NEFs from Nikon D60 and D80, so it does not appear to be camera-specific. I've checked the AP options and settings but nothing there makes a difference.
I also see that similar issues were reported with AP 1.6, and apparently resolved in 1.7. This makes AP 1.9.1 unusable for RAW processing.