JPEG XL development began in 2018, when the JPEG committee launched a call for proposals on next-generation image compression, to which seven proposals were submitted. Of the seven two stood out: Google’s PIK and Cloudinary’s FUIF proposal. The ingredients from both proposals were eventually combined and refined to design a new codec that was better than the sum of its parts.
[...]adoption of JPEG XL continued, in particular in image authoring software like Serif Affinity, Adobe Camera Raw, GIMP, Krita, etc. Unfortunately, Chrome’s decision has slowed wider adoption in web browsers of JPEG XL.
On June 5, 2023, at Apple’s annual Worldwide Developers Conference (WWDC23), a slide was presented listing new features of the Safari browser, and “JPEG XL” was on the slide. Not only is Safari 17 adding JPEG XL support, the new versions of iOS, iPadOS, macOS, watchOS, and visionOS will support JPEG XL.
There was a political decision from management to favor their own AVIF format over JPEG XL. A lot would have to happen before they’d overturn that.
With the current market share of Chrome-based browsers, there’s no market pressure for them to do anything they don’t want to do.