This isn’t really a bug. There was an update recently that allowed jumping. And together with that update there was the ability to place air collision to prevent just that. But a lot of the houses and buildings were build way before the jumping update and thus don’t use the air collision. The players just have to log in and place those to prevent that. Also, all the containers in the houses are locked and one was even locked by Rammy which previously wasn’t locked.
But after giving it some thought, it doesn’t really make sense to have doors at all if they can only do their job in conjunction with air collision tile flags. Therefore, doors will also create top-layer collision with one of the next updates.