The number refers to a specific issue tracker entry for TrueNAS , the popular open-source storage operating system. Specifically, it is a suggestion to automatically create a snapshot as part of an OS upgrade (NAS-125176).
If you are managing a TrueNAS system and want to support this feature:
Removes the human error of forgetting to manual backup before an update.
Until this is fully integrated as a "toggle" in the UI, include a Boot Pool Snapshot as a standard step in your maintenance checklist.