Hmmmm. Ideas from this thread: https://arduino.stackexchange.com/questions/66761/debouncing-a-button-with-interrupt

Instead of triggering the interrupt on “falling”, I trigger the interrupt on “change”. Then I keep track of whether the button is being pushed down or being released. I debounce both states (pushing or releasing) and only perform the user’s desired activity when the button state has gone to “down” after the debounce. But not when it has gone to “up” after the debounce.

If I’m not careful I could get into a stuck button state though.