I am seeing a bug with the use of iOS 18’s Customize Automatic setting.
When swiping from page view to page view forward and back, the apps’ icon version of dark or light change with each return to that page, constantly…first view the app’s icon is light, return view and it’s dark, then return a next time and it’s back to light.
Going further, switching the Customize dark/normal background setting (the sun icon in top left) resolves once clicked.