> X-Stat header that controls whether the server operates in enterprise mode.
Perhaps this header mentioned in the article is related, maybe that's the toggle for the enterprise mode? Seems there is at least traces of "enterprise mode" on the normal github servers.
There is no “the toggle”. Read the article. A GHES appliance (and github.com) is dozens of services working together, some of which act differently in ES mode, so there are toggles galore. But probably not a lot that can be toggled by user input :(