@noname, I can’t because I don’t know enough, but perhaps you can explain the following:
When using the colour picker under HSL in PhotoLab on the area that is of interest here and looks white on screen, it selects a red/yellow range.
If the image is opened in Darktable and:
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demosaic is set to “photosite color debug” (EDIT: just noticed also happens with other methods. Darktable was not rendering the whole image sometimes, so I didn’t see anything)
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“Visualize clipped highlights in a false color representation…” enabled
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threshold set to around 0.6 or lower (with the default method or segmentation based)
you can see something happening in the problematic area (on the marker pen it starts with a higher threshold):
