In cast you haven't solved the mystery yet..
I was having the same issue. I noticed a ♡ icon next to the suggested URL, I searched for a bookmark, but didn't find it... at first. Then I went back and checked in the bookmarks trash folder. BINGO! I emptied the trash, and the suggested link went away. Apparently, I bookmarked the incorrect page, through that bookmark in the trash, but never emptied the trash.