npm will now check the linked source commit and repository when you view a package's provenance information on If the linked source commit or repository cannot be found, an error displays at the top of the page and alongside the provenance information to let you know that provenance for this package can no longer be established. This can happen when a repository is deleted or made private.

Note: In future releases, publishing a public package with provenance from a private source repository will not be allowed.

Read more about viewing npm provenance and publishing with provenance.