some idiot Chromium engineer who worked on webp is blocking it from being put in. see jpegxl.info

on desktop install https://chrome.google.com/webstore/detail/jpeg-xl-viewer/bkhdlfmkaenamnlbpdfplekldlnghchp

on mobile choose a browser that has it already. Cromite is a good option https://github.com/uazo/cromite

iOS and Firefox users don't need to bother 

 iOS has ecosystem-wide full-ish support, but firefox only supports JXL behind a feature flag in their nightly builds. They have the same opinion as chromium but they arent that stupid to remove it entirely