Example: https://github.com/shryder/nano-node/runs/3163839612

invalid argument "ghcr.io/Shryder/nano-node/nano-env:base" for "-t, --tag" flag: invalid reference format: repository name must be lowercase
...
invalid argument "ghcr.io/Shryder/nano-node/nano-env:gcc" for "-t, --tag" flag: invalid reference format: repository name must be lowercase

I've changed my username now its all lower-case.