Webm is better in many ways, but it doesn't give you gif-like behavior I think. As in, you can't just include it in an <img> tag and a get an autoplaying looping video. Though you can simulate it with <video>.

Basically, .avif is an "animated image" format, like .gif, but .webm is only a video format.

edit: just realized .webp i think can be an animated image! So that seems like the alternative