Quick reason is, it happened just because of the new updated OS not able to decide between software CPU or hardware GPU. This is more visible in the app drawer when searching apps.
Usually, this encountered a flickering display when opening small apps and when using the keyboard or when watching website pages on the Chrome browser or it frequently happens in browsers when typing using the on-screen keyboards.
How to solve Screen Flickering Problem
1.Go to Settings >> More Tab >> About device. 2.Find "Build number" and click 6 times fast on it. 3.You will then get the message saying: "You are now a developer" 4.Come back to Home Screen, and then go back to Settings >> More Tab >> Now you will see the "Developer Options" 5.Now go to Developer options >> Drawing Section or Rendering Section >> Find "Turn off hardware overlays" or "disable hardware overlays" >> This will force the phone to always use GPU for screen compositing
