When running a native iOS application on macOS Silicon then if requires full screen is turned off then it can end up not being rendered correctly after a given size. To reproduce this can be done with any of the examples:

• Select iOS as build target and build (don't run)
• Open the generated Xcode project with Xcode 12 Beta 4
• Select My Mac (Designed for iPad) as build target
• In the target's General tab, disable Requires full screen (alternatively, in the Info.plist file, set UIRequiresFullScreen to false or NO.
• Run the app -> the iOS ARM app is now being natively run on macOS
• Enlarge or maximize the window size
• After a certain size has been reached, the canvas size doesn't increase anymore