Another clue: The “wait for network to be configured” seems like it might be a problem, but not the main one. On another run, I can see the server is trying to reach MAAS at the server’s IP! At least, 10.30.30.234 is not an IP address of any of my controllers.
I’ve tried looking through the code to see where this bogus URL might be coming from, but I’m running out of ideas. It looks strikingly similar to this Fedora / cloud-init bug from 2018: https://bugzilla.redhat.com/show_bug.cgi?id=1558641