Animation encoder transparency is broken
The easiest way to reproduce this is to run:
showanim -save butterfly.gif butterfly.ani
This example shows GIF encoding, but it looks like it's broken for all formats.
@LordOfXen, can you take a look at this?
Here's the butterfly animation I was using for testing: https://sweezy-cursors.com/cursor/orange-butterfly-animated/
Could you tell me what's exactly wrong with formats other than GIF?, I tried the butterfly GIF animation to create a WebP or PNG animation, and no transparency issues occurred.
I didn't verify that other formats were broken and I don't remember why I thought they would be affected. If you're not seeing any problems, we can ignore that feedback for now.
Oh, alright, they seem to work. I performed the same tests as with GIF, and the results were always correct animation outputs. (Quick note though, I only tested WebP and APNG, did not do the tests for AVIFS)