Enabling contrast, brightness and saturation grouping is affecting image
I've only noticed this on the attached RAW file, but in version 2.4.1 of Darktable, when you enable the brightness, contrast and saturation grouping tools the image histogram and preview is changed, even though no changes to the sliders have occurred. See the attached screenshots for an example.
#1 Updated by Christian Kanzian 22 days ago
I think that is per design.
darktable does not clamp color values to valid values by default. (https://www.darktable.org/usermanual/en/color_management.html#darktable_color_spaces)
Moduls are working in different color spaces and the conversion could cause such "artefacts" (https://www.darktable.org/usermanual/en/color_management.html#possible_color_artifacts).
The conversion takes place as soon as a single modul is turn on which is working in Lab color space.
You can try to turn on gamut cliping in the "input color profile" module like descripted in the manual or in this video tutorial:
Does this help?