“Performance configuration is now applied at runtime and no longer requires darktable to be restarted when changed.”
Almost 1,600 commits and 586 pull requests since 3.8, from volunteers, for free. Filmic v6 swaps forced desaturation for real gamut mapping, which is the kind of thing Adobe charges a subscription for. The catch is buried in the notes. The upgrade is one way, so back up your library first or lose the ability to go back.