If versioning is enabled on an S3 bucket Veeam Backup & Replication will only manage the versioning when Immutability is enabled within the Object Storage Repository and Object Lock is enabled for the bucket.
At this time, all buckets created within Backblaze have versioning enabled. As such it is required that that any Backblaze S3 buckets created for use with Veeam Backup and Replication must have Object Lock enabled at the time of creation and when added to Veeam Backup & Replication “Make recent backups immutable” must be enabled for the Object Storage Repository.
In Backblaze when creating a bucket:
In Veeam Backup & Replication when creating an Object Storage Repository: