I have the feed content type disabled, so it can't be that one. As for redirects/synonyms, I have not created any of these within the particular instance of VaultWiki that this anonymous page path issue was experienced.
I did come across something that may be a clue in the vw_path table.
The anonymous page (with itemid 59) appears there with a value of 101 in the vw_route.routeid column. Could this be it?