I have never seen a backup tool this fast!

[cornucopia]

I found this reply from Jarek very helpful

Best method to ensure valid snapshots: snapshot verify vs snapshot fix invalid-files

There are many verification methods, depending on what you need. In the order of lowest- to highest-level: kopia content verify - will ensure that content manager index structures are correct and that every index entry is backed by an existing file kopia content verify --download-percent=10 - same as above, but will download 10% of random contents and ensure they can be decrypted properly kopia snapshot verify - will ensure that directory structures in the repository are consistent by …

It explains the difference between snapshot and content verification, and illustrates how to verify a subset if you have a large repo.

Edit: just realised the docs cover it as well.

Verifying Validity of Snapshots/Repositories and Trying to Repair Any Corruption