@zyabin101 @Sylvhem About the APNG format, it was seen as redundant when it was released. There exist an older animated format based on PNG, the MNG. So those who already supported the MNG format were reluctant to support the new format made by Mozilla.

Also, the MNG/APNG format are not good for long animations, as they tend to be heavier than GIF. GIF are already heavy for long animations, and as such, mastodon automatically convert them into a video format.

The only point of using APNG over GIF is for getting a real alpha layer and not just a transparent color. However the alpha layer would be lost if converted to a video format.