The images of Gitlab-ee on Docker Hub are pruned, i.e. not all tags remain available.
See Docker Hub
Therefore it is good practice to backup the image you use with your backup, or you will be surprised that you cannot restore.
docker exec -it gitlab gitlab-backup restore BACKUP=Friday Unpacking backup ... done GitLab version mismatch: Your current GitLab version (13.10.3-ee) differs from the GitLab version in the backup! Please switch to the following version and try again: version: 13.10.0-ee