In the following documentation, lack of the note about the DeleteImageSetConfiguration should always be a subset of the ImageSetConfiguration used during mirroring.

Also, related to the above restriction, to avoid incorrect DeleteImageSetConfiguration setting, note that it is recommended to use the oc mirror delete command to create the DeleteImageSetConfiguration instead of creating it manually.

 https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/disconnected_environments/mirroring-in-disconnected-environments#oc-mirror-procedure-delete-v2_about-installing-oc-mirror-v2