>>106482961
Because unlike lossy webp, lossy avif doesn't have that retarded problem where it gives you a file bigger than the jpeg. Ironically lossless avif gives you a bigger filesize than lossless webp.

Jpeg xl is trying to fix this but there some images will still result in smaller file sizes via AVIF so it looks like we're practically speaking, stuck with both.

>>106363731
It's one of the true successors to JPG. Webp does okay but sometimes it produces files bigger than the JPG so it's gotten a lot of criticism for that.

Also JPG XL not only replaces JPG but PNG and GIF as well so it's a pretty cool image format if your CPU isn't a potato (ie i5-8400 or better). In some cases AVIF can do better but JPEG XL could honestly work for like 70-90% of your image compression needs depending on what sources they are. AVIF would be supplemental desu.