I purposefully gave the last frame a smaller hitbox so the player could feel that they are "almost through"... but maybe this should be changed? Open for feedback on this - do you think the blocks should have a full hitbox until they are broken?
I'd at least see if the change fixes the stump glitch because if its the cause of that glitch it could cause all sorts of other ones in the future.
Otherwise, I think the smaller hitbox gives the effect you were going for and seems fine to me.