It must probably be one of studio gear as you guess.Maybe only in the studio? Maybe he changed his gear? I don’t know...
John Mayer also has several PRS models, Fender models stomp boxes and doesn't use half of them on gigs either.As described on the Artist page, John Mayer is said to be using AxeFx.
However, a look at his set from the current 2022 tour shows that the AxeFx is not listed.
Does anyone have more detailed information?