If you go to c/homeimprovement@lemmy.world through midwest.social, it shows fewer subscribers in the sidebar than if you go straight to lemmy.world (https://midwest.social/c/homeimprovement@lemmy.world vs https://lemmy.world/c/homeimprovement). Also, there are posts that only show up when you look at c/homeimprovement@lemmy.world through the midwest.social instance, and are missing from the lemmy.world instance.
For example, this post: https://midwest.social/post/4242666 is nonexistent if you look at the homepage on lemmy.world: https://lemmy.world/c/homeimprovement. However, you can see it from the homepage on midwest.social: https://midwest.social/c/homeimprovement@lemmy.world.
I don’t know what the issue is with the post missing. But in regards to sub count - current implementation only shows the number of subs from your instance. The home instance of the community is the only one that shows the real number.