u/Vict0rMaitland

I took down some drywall to build a little shoe chubby in the wall. Now I'm putting back up the drywall. One spot is really confusing me - the bottom I can see the hole in the floor was 2 inches thick, for old school dry wall, but as it goes up it slowly turns into a one inch thick spot. How should I go about putting back up drywall there? Any advice?