Requested feature overview description.
Add a link to https://e621.net/users?commit=Search&search%5Bavatar_id%5D=[postid] in the Options or Related section of the post's page

Why would it be useful?
Quick shortcut to see which users have that post as their avatar

What part(s) of the site page(s) are affected?
Only the post itself

You know what's funny? That exact link was part of my original pr to add searching for avatars, but Earlopain requested it to be removed
https://github.com/e621ng/e621ng/pull/529