I think the article is slightly misleading: it says "Google has resumed work on JPEG XL", but I don't think they have - their announcement only says they "would welcome contributions" to implement JPEG XL support. In other words, Google won't do it themselves, but their new position is they're now willing to allow someone else to do the work.

It's technically correct. Googlers (at Google Research Zurich) have been working on jxl-rs, a Rust implementation of JPEG XL. Google Research has been involved in JPEG XL from the beginning, both in the design of the codec and in the implementation of libjxl and now jxl-rs.

But until now, the position of other Googlers (in the Chrome team) was that they didn't want to have JPEG XL support in Chrome. And that changed now. Which is a big deal.