I believe a client of ours is having the same issue, of having random pages popping up that are 404. They do appear to be found on google search results with random title tags, and metadata descriptions, but the page itself does not exist. I can’t delete them from WordPress, since those sites do not appear on WordPress sites, even though I look at all pages.
I’m currently using manual labor to delete those random 404 pages from the google search engine.
