This is very minor, and has possibly been like this forever…
We’re displaying the split category/subcategory badge in the docked title header, but not in the default non-scrolled title.
It seems like our “rule” elsewhere is to not show the split subcategory badge when the full parent category name is present (that’s what we do in the breadcrumb nav, for example). So when the title docks into the header, we shouldn’t split the subcategory badge to include the parent category.