You can probably ignore the navpopup there, it comes from my global pref page at Meta.
However, I dunno that I should see a hovercard when hovering on that  ref. It contains the article's lede.
- Ensure the gadget "References Tooltips" is disabled in https://en.wikipedia.org/wiki/Special:Preferences
- Ensure page previews is enabled in https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rendering
- Visit https://en.wikipedia.org/wiki/English_possessive
- Find "Note the distinction from the plural in nouns whose plural is irregular"
- Hover over 
- Expected: No page preview; Actual: page preview shows