cm-push reports Error: 403: insufficient_scope

[reb-xpat]

We are trying to push a tgz file to a gitlab registry using the cm-push plugin. The helm cm-push command ends with the error message 'Error: 403: insufficient_scope'. We have tried using --debug but don't get any more output.
The command is being run on a Windows 10 machine, that is running ubuntu in a WSL.
We saw similar behavior when running the same command on a virtual machine (ubuntu) on the same Windows box.
We were unable to reproduce the error running ubuntu/helm in a docker container on Mac.

We tried adding credentials with the -u -p switches to the helm cm-push command line.

The following commands were run to create the tgz file and push to the registry.
helm package my-package
helm repo index mypackage/ --url https://gitlab.com/api/v4/projects/12345678/packages/helm/my-package --merge index.yaml
helm repo add --username someuser --password someusers-token my-package https://gitlab.com/api/v4/projects/12345678/packages/helm/my-package
helm cm-push my-package.tgz my-package
We tried running a docker container with ubuntu:20.04 on the same Windows box outside of the WSL2 and saw the same behavior.
The helm version, 3.9.0.

Any ideas?