Not to mention, even if it proves satisfactory to the existing userbase, any new users will start with no history to draw inferences from, wouldn't that tend to imply that any existing users unaffected are essentially "grandfathered in", but with the same privacy concerns for everyone else in the long run?

they have already done this for at least the last year or so easily. I noticed it when I requested by data package last year, theres a clear area on it that infers both your gender and your age in it.

They are just acting like this is a "new system" but in reality its a system that have had for awhile now, just didn't have any public facing usage of it.

For anyone else that wants to see it themselves, and they have a discord takeout. its located at the very bottom in the events file in activity/analytics.

the end of the file shows json objects that indicate what your predicted age and gender is.

edit: I found this file isn't a static location, it is still in the activity/analytics directory in one of your event files, but you need to search "age" or "gender" to find it if it isn't at the bottom

They already do this for advertising. And it is extremely accurate.