About ten days ago, Google announced new rules around which search results will get reviews (stars) in their search results snippets. We saw a steep decline reviews rich results showing in the Google search results a couple days after the announcement. The decline has continued since according to the tracking tools.
Here are charts from the tools that track it showing even more loss over the past several days:
Joy Hawkins from Local Search Forums posted on Twitter recently “We’re now seeing a massive number of sites lose gold stars in the SERPS.” Indeed.
Forum discussion at Twitter and Local Search Forums.