At the moment e621's wiki page for furaffinity says
"Copyright: furaffinity
Furaffinity is an furry art website where many furry artists post their work and is one of the major source for the e621 site."

About 127 uploads at e621 are tagged with "furaffinity". I skimmed through all of them and only about 60 have FurAffinity content (show FA webpage in background, show FA's mascot, etc).

So about half seem to be tagged with FurAffinity only because the source of the image was FurAffinity.

What do you think of the wiki page for furaffinity being clarified to something like
"Uploads should be tagged with "furaffinity" if upload:
1) shows a FurAffinity webpage
2) shows FurAffinity's mascot
3) discusses FurAffinity
4) something similar
If there is no FurAffinity-relevant content shown in the upload, and the only FurAffinity (aka FA) relevance is that the source is at FA, then do NOT tag with furaffinity (just put FA source URL in the source field)."
?

Patreon tag had similar issue, where everyone was tagging content with patreon if there was only patreon url, content was from patreon, artist had patreon, patreon was mentioned in description, etc. and in none of those cases the tag wasn't supposed to be in there.

The wiki page was also in similar, only explaining what patreon is, not where the tag should be used:
https://e621.net/wiki/show/patreon?version=1
I revised the page to have examples, explain when the tag needs to be used, write down what counts as patreon logo and list of what to use instead in specific scenarios.
https://e621.net/wiki/show/patreon?version=5

Furaffinity page has only single revision and it was done by GONE_FOREVER, so assuming by their nickname they won't be touching it again. Feel free to do similar edit to the furaffinity wiki article and at least the post count isn't massive so that should be easy to go trough by hand.