When I look at another user's reviews, and filter by star rating, it works fine for the first page of listings. But it fails after that. For example, try https://www.imdb.com/user/ur32764997/reviews, filter on 7 stars, then try "load more" at the bottom. You'll get a mix of other star-rated films from then on. This happens for any reviewer that has enough to fill the first page.