Comparator still emiting redstone strength bug (Using on Crafter Block) /

I created a machine to craft a crafter using a crafter, as a joke. And I noticed that when the Crafter eject the output result, the comparator responsible for "notice" continued emiting redstone signal strength 9, remaining on, waiting for some update around. (When placing or changing a state of a block adjacent to it, it returned to the original value 0).