This is an "Orphan" page. Its core content has not been shared: what you see below is a loose collection of pages and page snippets that mention this page, as well as snippets of this page that were quoted elsewhere.
We've now had a few reports of people losing data when merging pages (usually they're changing a page title and getting a "this page exists would you like to merge" and the page does not in fact exist)
Working on identifying this bug, but if you get the Merge Pages warning, suggest copy/pasting that text to an external source first.