So to replicate this bug you must enable assistive touch. Then go to the camera app, click the assistive touch, from there you can already see constant animation lag, keep opening and closing the assistive touch, then feel the temperature on the back of your phone (below the camera), it will be blazing hot. Usually i turned off my phone immediately because i'm afraid to damage it.
Pretty sure this bug is from the beginning of iOS 11, right now i'm at 11.2.5 but it still there. I'm using iPhone 8 Plus
Pretty sure this bug is from the beginning of iOS 11, right now i'm at 11.2.5 but it still there. I'm using iPhone 8 Plus