Then you close the app that has this issue. You just need to press the recent applications menu (usually the first left button) in your phone. Usually when you open an app, you will see a black screen for few seconds and then app will crash with or without an error message.
It is one of the most common problem in android operating system. Common FL Studio Mobile App Problems and Troubleshooting Steps ✅ I'm getting black screen / white screen (blank screen) when I open FL Studio Mobile?