[JyrkiAlakuijala]

AVIF was a quick hack originally by Netflix by placing an AV1 frame into a HEIC container. I believe it was done in a few weeks of work.

AV1 was largely based on VP9/VP10 and was developed by a team working in Chrome organization.

JPEG XL main mode (VarDCT) and the JPEG recompression is largely developed by Google Research.

WebP as a format was based on VP8, a video codec built by On2 Technologies. On2 was bought by Google in 2010 -- a year before Google published WebP. The transparency and lossless encoding as well as non-video keyframe-by-keyframe animation were designed at Google. The On2 VP8 codec used initially in WebP lossy was not that suitable (too many artefacts) for photography transmission. Jeff Muizelaar wrote a great blog post about this. The codec for WebP were redesigned (without format) changes at Google, and kept improving significantly until around 2015 when it reached pretty good maturity.

(Personally, I don't like what it does to highly saturated dark colors, such as dark forests or dark red textures, but it is much much better than it was.)