Google decided to follow South Korean ruling allowing third-party in-app purchase methods in mobile apps.
Change is relevant to apps in South Korea only.
The South Korean government recently passed a law regarding app stores and billing systems for users in South Korea. We respect the decision of the National Assembly, and we are sharing some changes to respond to this new law, including giving developers that sell in-app digital goods and services the option to add an alternative in-app billing system alongside Google Play’s billing system for their users in South Korea. These changes will allow us to comply with the law, continue to invest in Android and Google Play, and provide the seamless, safe and trusted user experience billions of people expect from Google Play.Google Blog
Google will charge fee on transactions made via alternate systems. Fee is smaller than regular Google Pay billing, but still significant.
Service fees for distributing apps via Android and Google Play will continue to be based on digital sales on the platform. We recognize, however, that developers will incur costs to support their billing system, so when a user selects alternative billing, we will reduce the developer’s service fee by 4%. For example, for the vast majority of developers who pay 15% for transactions through Google Play's billing system, their service fee for transactions through the alternate billing system would be 11%. As another example, certain categories of apps participating in our Media Experience Program, such as an eBooks provider, will pay a 10% service fee for transactions made via Google Play’s billing system, but only 6% for transactions on an alternative system.Google Blog