Description of problem:

Relevant document is here: https://docs.openshift.com/container-platform/4.16/backup_and_restore/application_backup_and_restore/oadp-advanced-topics.html#oadp-pod-volume-backup_oadp-advanced-topics

The description of opt-in/opt-out suggests that these annotations are used to tell Velero which volumes to back up (or omit from backup).

This is incorrect. The opt-in/opt-out approach is used to allow velero to decide between filesystem backup and snapshot/datamover backup. With the opt-in approach, volumes not opted in use snapshot/datamover (i.e. that's the default), and volumes opted-in via annotation use filesystem backup (kopia or restic). With the opt-out approach, volumes not opted out use filesystem backup (i.e. that's the default) and volumes opted-out via annotation will be backed up via snapshot/datamover.

Also, the document says that the pod mounting the opted-out volumes will be excluded from backup. This is also incorrect – pods are never excluded as a result of these annotations.

Version-Release number of selected component (if applicable):