I updgraded docker and tried to re-run:
wordsmith@digitalwind-ubuntu-20:/var/discourse/containers$ docker --version
Docker version 27.5.1, build 9f9e405
wordsmith@digitalwind-ubuntu-20:/var/discourse/containers$ cd …
wordsmith@digitalwind-ubuntu-20:/var/discourse$ sudo ./launcher app rebuild
x86_64 arch detected.
ERROR: containers/rebuild.yml does not exist or is not readable.
Available configs ( app )
wordsmith@digitalwind-ubuntu-20:/var/discourse$