Orphan page
What this means
No other crawled page links to this indexable URL, so it was only reachable via the sitemap or the crawl seed. Orphans receive no internal link equity and are hard to discover.
How to fix it
Link to the page from relevant content, a hub page, or navigation — or retire it if it should not exist.
Fix effort
This check needs review: the change can be drafted for you, but a person has to approve the wording or choose the target before it ships.
Authoritative source
https://developers.google.com/search/docs/crawling-indexing/links-crawlable
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