Hi, keep the vault, stop protection with retain data, and restore from that same vault when needed. This keeps all existing backups, lets you restore anytime, and gives you control over cost and access.
Before or right after migration, choose between stopping protection with data retention (backups kept indefinitely, billed) or keeping protection temporarily with a 1-year policy to let Azure prune points automatically. If you're cost-sensitive, move recovery points to the Archive tier before stopping protection: once you stop, you can't archive anymore. Be aware of archive restore delays and the 180-day early deletion fee.
Enable Immutable Vault (with lock if needed) and soft delete to prevent accidental data loss. Later, restore VMs or disks from the vault via the Backup pane, even if they're in "Stop protection (retain data)". For restore access, assign roles like Backup Operator or Disk Restore Operator to your IT/helpdesk.
You'll still pay for Protected Instance and storage, even if backups aren't active. Archive helps with storage cost, but not PI fees.
To manage this cleanly: take a final backup, archive eligible points, stop protection with retain, enable immutability, track who can restore, and delete retained data after 12 months.