Early last year, Google rolled out a new monetization method for developers to take advantage of in their apps. The woefully non-descriptive "rewarded products" allowed for things like watching videos to get in-game currency or extra lives — you get the idea. For simplicity, it was built right into the Google Play Billing Library, but Google has just announced that it will be deprecating the feature on April 21st, 2020, about two months from now.
An example of the rewarded products.
Google didn't hype up the detail too much in its initial announcement last year, but rewarded products were actually just in beta, and following feedback from the beta program, the company has decided not to continue.
Ad requests after that date won't be fulfilled, and you will no longer be able to view or manage rewarded products in the Play Console. Developers will also need to provide a payout method for revenue from rewarded products before April 21st to receive their final payout, and a one-time exemption for the minimum balance for payout will be allowed. More details for developers are available at the source link below.