One issue we have found is that after entering an incorrect PIN, there is some issues with which placeholder is shown highlighted. If the user taps quickly on another number button after entering the fourth key, the animation shows the first placeholder show highlighted during the animation, then when another selection is made after the animation the second placeholder is highlighted, and the first is not. Issue is that even though there is a check to enter the text until after the animation you need to first disable after an entry, and keep it disabled until after the animation when the 4th character is entered.
One issue we have found is that after entering an incorrect PIN, there is some issues with which placeholder is shown highlighted. If the user taps quickly on another number button after entering the fourth key, the animation shows the first placeholder show highlighted during the animation, then when another selection is made after the animation the second placeholder is highlighted, and the first is not. Issue is that even though there is a check to enter the text until after the animation you need to first disable after an entry, and keep it disabled until after the animation when the 4th character is entered.