GitHub's Docker registry (which used the namespace docker.pkg.github.com) has been replaced by the Container registry (which uses the namespace https://ghcr.io). The Container registry offers benefits such as granular permissions and storage optimizations for Docker images.
Docker images previously stored in the Docker registry are being automatically migrated into the Container registry. For more information, see Docker 레지스트리에서 컨테이너 레지스트리로 마이그레이션 and 컨테이너 레지스트리 작업.