Hey.. So, lately I have seen a bunch of fandom art in art galleries and avatars lately. Was a rule changed or something?

Possibly?? I'm not exactly sure, but I don't think it has..

As Hurri said, I don't think that there's been a rule change regarding the fandom side of things, just that cartoony human art is now allowed. :P Maybe that's why there's more 'fandom art' is because of the more cartoony stuff allowed?

As far as I'm aware, there's been no change to the rule.
However there might be a few things that are only loosely defined as fandom as therefore not being taken down, or the mods aren't aware they're fandom. A lot of the DreamSMP/Minecraft fanart seems to fit this, but there's likely others as well.

Probably, I haven't seen any yet, I don't think the rules have changed for fandom.