Disallowing developers from using in-app billing for donations, while also barring them from linking to external donation platforms, puts open source projects in a difficult position, and appears to be overly hostile towards funding open source development.
Google must clarify their position on whether they allow donation links in apps published on Google Play. The app takedowns [2] of the last few days show that this is a significant development, and it is of great importance for all open source developers.
It's best to publicly document the messages you receive during app takedowns, since app store policies are often vague, it's easy for reviewers to make mistakes, and having a clear reference for these decisions also helps the public assess the validity of the takedown.
[1] https://play.google.com/about/monetization-ads/
> Here are some examples of products not currently supported by Google Play In-app Billing:
> One time-payments, including peer-to-peer payments, online auctions, and donations.