A great codec but not the best for the web. For typical web use AVIF is almost always better.
The case against JPEG XL https://giannirosato.com/blog/post/case-against-jxl/
The case against JPEG XL https://giannirosato.com/blog/post/case-against-jxl/
There are some unanswered questions about the methodology used, the resources spent on development of the respective encoders is not taken into consideration, the future developments of JPEG XL encoding are written off as too costly and the author’s opinion on what kind of content is appropriate for the web is quite subjective. See also the recent discussion:
AV1 was designed to deliver a pretty good new frame with as low as possible budget, and further video frames could bring the missing detail later. AVIF/AV1 has much more aggressive filtering and more features that are well suited for low bit budgets -- but also is missing features that are needed to get things right at higher quality.
JPEG XL can control filter strenght at 8x8 pixel resolution, whereas in AVIF filter strenght is constant over a 64x64 block.
Similarly, adaptive quantization is more fine grained in JPEG XL.
Finally, adaptive quantization automatically modulates the filter strength in JPEG XL (but not in AVIF), so the same data does not need to be sent twice for this purpose.
All of these three differences are visible in bit budgets only in the higher quality images.