Those words were about the JPEG recompressor (Brunsli) specifically, which saves about 22% but has a smoother transition from today's .jpg world than any of the new lossy formats; you can bit-for-bit reconstruct the original JPEG from the Brunsli-compressed one, and CPU encoding is certainly much faster than for AVIF. You could even implement Brunsli transparently to the user, as a Content-Encoding (so right click still saves .jpg), and Chrome had an issue open to consider doing that before they backed out JXL support.