Quando você adiciona um nível de aninhamento adicional, todas as categorias, incluindo categorias filhas, são exibidas na página de categorias

[pfaffman (Jay Pfaffman)]

It’s generally considered a bad idea to have more than a couple hundred categories. Maybe have a look at It’s Time We Talked About Tags. The sub sub category feature is largely unsupported last I knew, but perhaps there’s a way to hide them as you wish.