I don't understand what you're trying to say. Mozilla said over a year ago that they would support JXL as soon as there's a fast memory safe decoder that will be supported.

Google on the other hand never expressed any desire to support JXL at all, regardless of the implementation. Only just now after the PDF Association announced that PDF would be using JXL, did they decide to support JXL on the web.

> avif is just better for typical web image quality, it produces better looking images and its artifacts aren't as annoying (smoothing instead of blocking and ringing around sharp edges).

AVIF is certainly better for the level of quality that Google wants you to use, but in reality, images on the web are much higher quality than that.

And JXL is pretty good if you want smoothing, in fact libjxl's defaults have gotten so overly smooth recently that it's considered a problem which they're in the process of fixing.