The screenshot says that the violation is on the other part of the policy: "Google Play's billing system must not be used in cases where:... payments include p

The screenshot says that the violation is on the other part of the policy: "Google Play's billing system must not be used in cases where:... payments include peer-to-peer payments, online auctions, and tax exempt donations;" That is, according to the screenshot in the GitHub PR, the app was removed for using the Google Play billing system when they shouldn't be using it. It was not removed for failing to use the Google Play Billing system when they should have been. I have no idea how they might have been using Google Play billing. There is no billing code on GitHub that I see. Maybe they turned on billing on the Play Store accidentally, or maybe the screenshot has the wrong policy violation.