Unable to download Rubygem hosted on GitHub Registry

Hi there,
I have an action that builds a Docker image for a Ruby app.

    - name: Publish to GitHub Container Registry
      uses: info/publish-docker-image-to-github-container-registry-action@2021.2
        rubygems_pat: ${{ secrets.RR_PAT }}

The image is built as

docker build --build-arg RELEASE_TAG=${RELEASE_TAG} --build-arg RR_PAT=${INPUT_RUBYGEMS_PAT} --tag ghcr.io/${GITHUB_REPOSITORY}:${RELEASE_TAG} 

and finally, in my Dockerfile I have

bundle config https://rubygems.pkg.github.com/info info:${RR_PAT}

Everything has worked fine until the last time I tried to build the image (about six months ago).
Today when I run the action, I get

Fetching gem metadata from https://rubygems.pkg.github.com/info/.

Bad username or password for
Please double-check your credentials and correct them.
The command '/bin/sh -c bundle config --local frozen 1 &&     bundle config --local without development test &&     bundle config https://rubygems.pkg.github.com/info info:${RR_PAT} &&     bundle install -j4 --retry 3 &&     bundle clean --force &&     rm -rf /usr/local/bundle/cache/*.gem &&     find /usr/local/bundle/gems/ -name "*.c" -delete &&     find /usr/local/bundle/gems/ -name "*.o" -delete' returned a non-zero code: 17

The repo has a secret named RR_PAT with repo and read packages permissions.

Am I missing anything here?