Backup the gitlab docker image or you might not be able to restore

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

Which tag do you miss? Unless it is a really old version it is available on Docker Hub.

I was looking for 13.10.0 on Docker Hub

It is still there