I guess it’s not a very widely requested feature? It’s interesting to me that Avelon is literally the only iOS app among the many that exist so far that has been able to enable GIFs automatically animating and displaying on the timeline instead of just displaying a link to the GIFs location. I prefer a couple other apps over Avelon in terms of other features but I still end up just staying with Avelon because of this one feature none of the other apps have.
Also, I don’t really expect anyone to know the actual answer to my question I’m mostly just venting and hoping to get this noticed by some app developers.
!arctic@lemmy.world supports in-line gifs/webp/videos/etc, basically all media types supported by iOS except for webm. I would assume most clients are only displaying the thumbnails in-line to reduce data consumption, and memory requirements, but that is just a guess.