What is considered as active ? Is someone connecting to his account and lurking considered active ? Or, someone who just up/downvote without commenting or posting ?
programming.dev changed how active users are calculated on their instance to include voters as well as posters & commentators. It's a massive difference - programming_humor went from about 700 monthly active users to about 7000, for example.
Viewing communities from other instances from programming.dev's perspective will give a figure that includes voting activity.