Well, this tag is not the “latest”, but the latest of its kind, though (almost?) non of the tags currently published on https://hub.docker.com/_/docker are available at the moment.
So, if you want to experience something new, just type docker pull docker:27.4.0
in your terminal.
Ticket has been opened: Pulling published tags (eg.: latest) is denied until vulnerability scans are finished · Issue #2426 · docker/hub-feedback · GitHub