Here’s the Moz graph:
When Search Engine Land asked Google about this last week, Google said that they were currently “looking into it and will let you know when we have more details.”
So is Google intentionally removing these star reviews from their search results? Maybe it is, maybe it isn’t But, it seems that a huge percentage of the queries that Moz has been tracking shows there is a significant decline in review snippets. With this information, this could mean that it’s merely a bug. Either way, hopefully a statement will come out of Google soon to let us know what is going on.