iPhone passcode keyboard rendering bug
Years pass, but Apple just wouldn’t fix this bug in iOS. When the iPhone asks you for the passcode, it shows the keyboard where system keys’ borders aren’t semitransparent:
You may think that it is so by design, but no: if you touch the keyboard, all keys’ border re-render normally, with thin borders.
And sometimes the keyboard is rendered fine initially:
Does nobody in Apple use alphanumeric passcodes? The numeric ones you usually see others type from three-meters distance. Since there is Touch ID and the passcode is rarely asked for, there is no reason to use the numeric ones.