Yes and no. I am being served different images per connection. A VPN connection gets me a .gif file. One Onion / Tor circuit gets me the same .gif file whilst a third Onion/Tor circuit gets me a ".jpg" file.
The .jpg file is of course a gif. But they are not the same file but different extensions to be clear - different dimensions as well as file size.
I made an avatar for someone the other day and it showed up for some people seemingly quickly whilst for me it only showed up much later. And this was not an issue of a cached version of the image, I made sure of that. I had thought perhaps it was a TOR vs. VPN issue but now testing with yours I see that even via two TOR connections it can be different.
There is clearly some propagation delay going on since the new system but more than that, perhaps, as there is a different file extension being applied (same image name however).
As an aside, the site does support animated .webp which is what I have begun using for animated avatars I've made here. There's an oddity though in that they are re-encoded no matter what I do and something about the re-encoding strips out frame delays. I know this because I wanted to have an animated image that only changed after a long delay. A bit of a "did I just see that?" effect on people. But that proved impossible. I could do it by adding lots of repeated frames at the start of the animation but then the file size was huge. Or I could just encode a ten minute delay between the first and second frame (something you can do with .webp but not .gif). However, whatever forced re-encoding Null is doing, strips that. And the re-encoding happens no matter how small I made the image (data and dimensions) so far as I could tell.
EDIT: I half feel this is worth raising with Null, as you're the second person this has confused now.
EDIT EDIT: I raised this in the Technical Grievances thread here. Maybe he'll address it maybe not, but he can't if he doesn't know about it. Something funky with propagating images between the different VPS's I'd guess.
EDIT EDIT EDIT:
Funny you mention it. Mine isn't displaying properly either. There's the little bit on the left that sticks for half the frames and it wasn't like that when I made it.
All images seem to get re-encoded whether they are small enough to be avatars or not. I'm interested technically in what is happening here. Is it that little white leaf thing centre-height left edge that flashes in and out that you're talking about? That wasn't there in the original?
