Reviews left on Google play (and the App store?) can be marked as helpful or not. Using this feature helps boost those reviews higher in what users see when they look at the app’s reviews and gives it more impact on the overall app rating.

If there are reviews which mention features that concern you or that you think others should know about, like the API changes or Reddit’s handling of personal information, give them a thumbs up. Likewise, if a review isn’t helpful, make sure you say so. This pushes it lower and makes it less impactful on the app’s score.