I switched to Samsung for a better gaming experience but my iPhone 6s Plus ran my FPS game better, and now after the update the Note 9 is even further behind.
I understand how forcing an app designed for full screen into a smaller screen mode can cause issues, but since the One UI update my fav game isn't configurable, and forces full screen which causes unresponsiveness in the corners and edges. And unfortunately the joystick area isn't configurable in game. So unless there's an app or an override I'm missing, it looks like Samsung is putting it on the developers to fix, and if so it's pretty lame. Coincidentally, prior to the update I unkownigly changed the app to full screen, had the same problems, but once I realized I was able to switch back. So in my case the update sucks so far.
If anyone knows of a workaround I would appreciate the feedback.
I have double checked on my Note 9 and full screen works for the games I paly such as Clash of the Clans and Sim City. It works for me and these games in the corners and edges...I have lost a few battles and buildings trying this out!
I guess you have tried adjusting the settings in display.