Error with docker pull command - mediaType error

I'm trying to pull Ubuntu and getting the following error.

mediaType in manifest should be 'application/vnd.docker.distribution.manifest.v2+json' not 'application/vnd.oci.image.manifest.v1+json'

I'm running Docker version 20.10.12, build 20.10.12-0ubuntu2~18.04.1

This issue has only recently appeared.

I've just tried pulling Redis, and that worked.

Any ideas?