Description of problem:
If a migration is performed and Backups are created that reference a BSL, and then that BSL is deleted and/or replaced by a new one, but the backups remain on the cluster (or are synced from the same s3 bucket), you will often see the following error in the logs as velero attempts to reconcile said Backup:

"Error checking repository for stale locks"... "error getting backup storage location: backupstoragelocation.velero.io \"my-bsl\" not found".

Often users may be troubleshooting a failed migration and will latch onto this error in the logs, because on the surface it appears to be significant, when actually it's a red herring and there is likely a different root problem at play.

We'd like to get this documented in the troubleshooting tips of the best practices, as we've often has this brought to us as a question.

Version-Release number of selected component (if applicable):
1.4.0