What’s the difference between “parent” and “category_parent” in a WP_Term object?
The properties prefixed with category_ or cat_ are there for backwards compatibility. Taxonomies and terms were introduced in WordPress 2.3 (11 years ago) and categories were converted into a taxonomy at that time. Prior to this categories had their own properties (the ones with the aforementioned prefixes). For backwards compatibility, the _make_cat_compat() function is used … Read more