This inefficiency occurs when a protected resource (such as a virtual machine, database, or file share) is decommissioned without explicitly stopping backup protection. In these cases, Azure Backup continues to retain existing recovery points in the vault until the retention policy expires. Although the source resource no longer exists, backup storage remains allocated and billable, resulting in unnecessary ongoing costs.
This pattern is common when infrastructure is deleted outside of a formal decommissioning process or when backup ownership is unclear.