New compressed media formats always travel a decade-long path from either (1) obscurity → contender → universal support or (2) obscurity → contender → forgotten curiosity. AV1 is on one path, WebP is on another.
WebP remains fairly esoteric after 15 years, has always been a solution in search of a problem, and isn’t even universally supported in products by its owner.
AV1 was created and is backed by many companies via a non-profit industry consortium, solves real problems, and its momentum continues to grow. https://bitmovin.com/blog/av1-playback-support/
Funnily enough, JPEG2000-support was eventually removed everywhere. I assume the only reason this didn't happen with WebP as well is Google pushing and keeping it in Chrome.
Only support for decoding and from A17 Pro and M3 onwards, I believe? Going to be a few years before that's commonly available (he says from the work M1 Pro.)