A fair analogy would be: "when was upstream code of the filesystem was last updated?".
To that question, I doubt one would find a polular filesystem that was updated longer than 1 year ago (maybe I'm too liberal).
# zpool history | grep upgrade
Looks like last May.
That's the on-disk format, you probably updated the actual driver code a lot more recently than that
They didn't specify what kind of update, but in this case no, I'm on zfs-2.2.3, which was released in February. I'd have to go check out when it was marked stable by Gentoo and I actually updated. (I do occasionally have to rebuild whatever version I'm on when upgrading kernel versions.)
What was in that update that you are worried about this missing?