Podman has no default registry. flomp/wanderer-db:v0.21.0 fails with “no unqualified-search registries are defined”.
Use the full name: docker.io/flomp/wanderer-db:v0.21.0. Or set unqualified-search-registries in ~/.config/containers/registries.conf.
Old containers still ran because the images were already local, so no name resolution was needed. If a tag is not found, try it without the v.