Yeah, to be clear that's "of all time". Like, if we listed the greatest human achievements of all time - fire, gunpowder, antibiotics, computers, vaccines, the internet, etc. - that list would not be expected to change daily or even once a century.:-)

Also, every single one is either 10 or 11 months old - with only one exception being 9 months. That is obviously some kind of spike related to the Rexodus:-P.

The Fediverse is much older than 12 months btw - your list contains posts from outside of Aussie.zone so it's not looking at Local but rather All, so it includes those, which you can get to by sorting by Old.

TLDR: "top of all time" is not intended to be anyone's default search - Top or Active or New would be much better choices.