When a Google Doc is briefly made public, services like LinkedIn can access its metadata — such as title and thumbnail — through standard Open Graph tags. LinkedIn caches this metadata for about a week. Even if the doc is later made private or restricted to a specific Google Workspace, LinkedIn will still show the cached preview. It doesn’t mean LinkedIn has special access or that Google is leaking anything; it’s just a consequence of how caching and metadata scraping work. This behavior is expected and not considered a security issue.