MANIFEST_INVALID: manifest invalid; map[message:failed to parse manifest: manifest data does not match schema: 'application/vnd.dev.cosign.simplesigning.v1+json' is not one of ['application/vnd.docker.image.rootfs.diff.tar.gzip', 'application/vnd.docker.image.rootfs.foreign.diff.tar.gzip']

Failed validating 'enum' in schema['properties']['layers']['items']['properties']['mediaType']:
    {'description': 'The MIME type of the referenced object. This should '
                    'generally be '
                    'application/vnd.docker.image.rootfs.diff.tar.gzip. '
                    'Layers of type '
                    'application/vnd.docker.image.rootfs.foreign.diff.tar.gzip '
                    'may be pulled from a remote location but they should '
                    'never be pushed.',
     'enum': ['application/vnd.docker.image.rootfs.diff.tar.gzip',
              'application/vnd.docker.image.rootfs.foreign.diff.tar.gzip'],
     'type': 'string'}

On instance['layers'][0]['mediaType']:
    'application/vnd.dev.cosign.simplesigning.v1+json']