npub13th8my8lguhxpcf47csvddmk66ny7uzss7p2ku7gvawjmnf8d70q507dkj (npub13th…7dkj) packages.guix.gnu.org is backed by a different service. The main differences are: the front-end does not require JS (that was the main requirement), the backend is implemented by talking to the Data Service (instead of talking to a Guix process), and it only knows about the ‘guix’ channel.
In short: different goals and different design choices.