The in the documentation stated procedure to pull the security manifests for disconnected environments does not work as intended (https://access.redhat.com/documentation/en-us/red_hat_quay/3.5/html/manage_red_hat_quay/clair-intro2#clair-disconnected).

This command produced a json file called "updaters.gz": podman run -it --rm -v /etc/clairv4/config:/cfg:Z -v /path/to/output/directory:/updaters:Z --entrypoint /bin/clairctl registry.redhat.io/quay/clair-rhel8:v3.5.5 --config /cfg/config.yaml export-updaters /updaters/updaters.gz

"file updaters.gz 

updaters.gz: JSON data"

However the importer command does expect an archive. The workaround is to zip it again before importing it e.g. "mv updaters.gz updaters && gzip updaters".

Clair Image Version: 3.5.5