A new PNG spec

Seems a bit too late? And also, JPEG XL supports all the features and uses already advanced compression (finite-state entropy, like ZStandard). It offers lossy and lossless compression, animated pictures, HDR, EXIF etc.

There is just no need for a PNG update, just adopt JPEG XL.

I really don’t get it. Why, but why? It’s already confusing as hell, why create yet another standard (variant) with no unique selling point?

JPEG XL is not a "variant", it is a completely new algorithm that is also fully backwards-compatible with every single JPEG already out there, of which there are probably billions at this point.

It also has pretty much every feature desired in an image standard. It is future-proofed.

You can losslessly re-compress a JPEG into a JPEG-XL file and gain space.

It is a worthy successor (while also being vastly superior to) JPEG.

Is there any risk that if I open a JPEG-XL in something that knows what a JPEG is but not what a JPEG-XL is and then save it, it'll get lossy compressed? Backwards compatibility is awesome, but I know that if I save/upload/share/copy a PNG, it shouldn't change without explicit edits, right?

a sw that does not know what jpeg xl is, will not be able to open jxl files. How would it?

Not sure what the previous poster meant with “backward compatible” here. jxl is a different format. It can include every information a jpeg includes, which then maybe qualifies as “backward compatible” but it still is a different format.