Google is shutting down Google App Maker, a tool that allows you to make custom apps for your business. App Maker is included with G Suite Business and Enterprise editions, as well as with G Suite for Education.
Starting today, January 27, 2020, App maker is no longer under active development. However, critical bugs will still be addressed by Google. After April 15, 2020, you will no longer be able to create new apps. On January 19, 2021, existing apps made with App Maker will no longer work.
Google posted an advisory in their help section with the timeline as well as some additional recommendations:
Google recommends that you migrate your existing app to AppSheet, Apps Script, Google Forms, or App Engine, as they offer similar functionality. If you collect data, then you’ll want to move over to Google Forms. Keep in mind, though, that Google Forms isn’t really secure, so you’ll need to make sure that sensitive information is not passed via Google Forms.