TL:DW, JPEG is getting old in the tooth, which prompted the creation of JPEG XL, which is a fairly future-proof new compression standard that can compress images to the same file size or smaller than regular JPEG while having massively higher quality.
However, JPEG XL support was removed from Google Chrome based browsers in favor of AVIF, a standalone image compression derived from the AV1 video compression codec that is decidedly not future-proof, having some hard-coded limitations, as well as missing some very nice to have features that JPEG XL offers such as progressive image loading and lower hardware requirements. The result of this is that JPEG XL adoption will be severely hamstrung by Google’s decision, which is ultimately pretty lame.