So, I just tried this:
I took the history all the way back to “original” and compressed the history stack. This gives that there are no out-of-gamut pixels, and a very dark image (expected).
But the pipeline on the right still shows several modules as active. The one lowest in the stack is “raw black/white point”. darkroom does not allow me to deactivate this module. And when I click on it, the out-of-gamut pixels are highlighted.
All four black levels are shown as 150 in the raw black/white point module. White is shown as 3880. So, I think you may be suggesting to change those 150s to something else. I will play with it and see what happens.
PS - If I change them all to 141, there are about three highlighted out-of-gamut pixels. If I change them to 140, there are none.