The question gets asked while you are looking at a bucket, and answering it used to mean going to the Backups page and matching names by eye.

Open any bucket or server drive and there is now a Backups tab:

• •What protects this — the jobs that copy it somewhere else, when each last ran, and whether it succeeded.
• •What this protects — because a bucket that *receives* a backup is holding someone else's copies, and that is a different fact about it. Direction is carried rather than flattened.
• •Partial cover reads as partial. A job that copies one folder inside a bucket does not turn the header green — it says which part is covered.
• •No cover at all offers to create a job, deep-linked to the real form with this bucket already filled in as the source.

Coverage is read from the same place the protection board reads it, so the two can't disagree — including the case where a drive is protected by a migration rather than a backup job.