I used to publish gem packages to GitHub Packages using the following GitHub Actions and it was always successful.
name: Deploy to Github Packages
on:
  release:
    types:
      - published
env:
  ORGANIZATION: MYGITHUBNAME
  RELEASE_TAG_NAME: ${{ github.event.release.tag_name }}
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@master
      - name: Set up JDK 8
        uses: actions/setup-java@v3
        with:
          java-version: 8
          distribution: temurin
      - name: gradlew build
        run: |
          VERSION=$(echo $RELEASE_TAG_NAME | sed -E 's/(v)(.*)/\2/')
          ./gradlew gem -Pversion=$VERSION
      - name: Set up Ruby
        uses: actions/setup-ruby@v1
        with:
          ruby-version: 3.0
      - name: Setup Release Credentials
        env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
        run: |
          mkdir -p $HOME/.gem
          touch $HOME/.gem/credentials
          chmod 600 $HOME/.gem/credentials
          echo "---" >$HOME/.gem/credentials
          echo ":github: Bearer ${GITHUB_TOKEN}" >> $HOME/.gem/credentials
      - name: Publish Gem to GitHub Packages
        run: |
          PACKAGE=$(find build/gems -type f | sort | tail -n 1)
          gem push --KEY github --host https://rubygems.pkg.github.com/${ORGANIZATION} ${PACKAGE}`
However, with the repository I created today, it suddenly stopped working. Also, when I create it in an existing repository, it succeeds.
The error message when it fails is:
Pushing gem to https://rubygems.pkg.github.com/MYGITHUBNAME...
Your request could not be authenticated by the GitHub Packages service. Please ensure your access token is valid and has the appropriate scopes configured.
Error: Process completed with exit code 1.
When I use PAT to push the gem from my local environment, it succeeds, but it doesn't appear in the "packages" of the repository.
If anyone knows what is causing this, please let me know. Thank you.
- Unified repository and gem names (failed)
 - I cloned the repository where 
gem pushwas successful and tried with a different repository and Gem name (failed)