Actualicé docker e intenté volver a ejecutar:
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
Se detectó la arquitectura x86_64.
ERROR: containers/rebuild.yml no existe o no es legible.
Configs disponibles ( app )
wordsmith@digitalwind-ubuntu-20:/var/discourse$