but AVIF is the one Google, Apple, Edge, Firefox are pushing...
Let's not be misleading here :)
All the existing JPEG files can be converted to JPEG XL while gaining 20% size and still having all the exact same data. There are, what, tens or hundreds of billions of JPEG files out there for which the "original" (RAW or anything) is long gone (or never existed) and people don't want a "photocopy of a photocopy".
You can even decompress the JPEG XL back to the original JPEG file, bit for bit.
For that alone there shouldn't be any question: it's a wonderful feature.
In addition to that Apple / Safari are going to support JPEG XL and there are huge number of applications supporting that format.
People don't want this "over" existing formats. They want this in addition to other formats.
And I think they'll get it.
Chrome team themselves quoted no interest of those browsers as the reason for removal of the flagged code. Seems like an obvious way to pressure Google into supporing JXL would be to get Mozilla to launch their support, together with Edge and Safari?
However Mozilla has not completely dropped the feature like Google.
Chromium's JPEG XL feature request is marked wontfix but still possible to comment or express interest (star the bug).