Hmm. I'm certain that they've just failed on lemmy.today's vanilla Lemmy Web UI, not converted.

goes to test

I just created a test (non-animated) gif. Trying to upload it just fails

that is, one can select it and try to upload it, but the Web UI never inserts the uploaded image URL in the textbox.

Here it is on catbox.moe:

If I convert it to a PNG, a format that pict-rs does understand, it uploads without being converted to WebP:

Maybe it's something unique to lemmy.blahaj.zone?

EDIT: There's an option in the docker/docker-compose.yml in the lemmy git repo showing an example of how to add an option to force pict-rs to convert everything to WebP. So my bet is that lemmy.blahaj.zone has done that:

https://github.com/LemmyNet/lemmy/blob/main/docker/docker-compose.yml

# we can set options to pictrs like this, here we set max. image size and forced format for conversion                                                                                                                                                      
# entrypoint: /sbin/tini -- /usr/local/bin/pict-rs -p /mnt -m 4 --image-format webp

EDIT2: @Ada@lemmy.blahaj.zone would know.