If you create a Style, “gamma” gets included, set on (at least on my system).
But if you search for it as a module, it’s not there.
Should I keep it in my Style?, and keep it on?
Gamma use to apply the display profile before output color profile existed (probably around dt 0.9). Now, it only converts 32 bits float pixels from the pipeline to 8 bits integers for display preview. Don’t bother about it, it’s 100% technical stuff that used to be hidden, but now appears.