If while editing an article, you change its "watchlisted" status, the star will be inconsistent after the article reloads.

The problem happens when you check the "watch this page" check mark at the bottom for an article you weren't watching previously, or when you uncheck it while editing an article that was in your watchlist up to that point.
After pressing "Publish changes", when the article reloads, the star will show the status previous to the edit, not taking into account the aforementioned change.

If the page is reloaded manually, the indicator will be corrected.