Allow: .webm for animations, Yes? Like: .gif , info: https://en.wikipedia.org/wiki/WebM
and allow .webp .avif for images dev info: https://en.wikipedia.org/wiki/WebP
(short >256 color paletts/gradients, less jpg artifacts effects, smaller than png)
Viewing post in Creating a GIF for your game
.webm is a video format that can include audio. On a properly configured web browser, it should require an extra click to play because it is never acceptable for a web browser to auto-play videos with audio. It is therefore not a replacement for animated image formats (gif, apng) which never contain audio and can be auto-played.
(Lossless) .webp, on the other hand, should be the default image format everywhere.