JXL is the best image codec we have so far and it’s not even close. I did a breakdown on some of its benefits here. JXL can losslessly convert PNG, JPG, and GIF into itself, and can losslessly send them back the other way too. The main downside is that Google has been blocking its adoption by keeping support out of Chromium in favor of pushing AVIF, which started a chicken and egg problem of no one wanting to use it until everyone else started using it too. If you want to be an early adopter you can feel free to use JXL, but just know that 3rd party software support is still maturing.
Something you might find interesting is that the original JPEG is such a badass format that they’ve taken a lot of their findings from JXL and made a badass JPEG encoder with it named jpegli. Oddly, jpegli-based JPEGs are not yet able to be losslessly-compressed into JXL files, per this issue - hopefully that will be fixed at some point.
Everyone fully missing the point here. This is the banner image for [email protected] (that’s not where we are right now for the record), and it has a normal JPEG size of 7.7MB. When it’s served as WebP it’s 3.8MB. OP is correct that this is very stupid and wasteful for a web content image. It’s a triple-monitor 1440p wallpaper that’s used verbatim, and it should instead be compressed down to be bandwidth-friendly. I was able to get it to 1.4MB at JPEG quality 80, and when swapping it out in dev tools and performing A/B testing I can’t tell the difference. This should be brought to the attention of a mod on that community so it can stop sucking people’s data for no reason.