wp_xx_categories() doesn't pad counts correctly when a sub-category exists

[wildworks]

I fond this issue while researching gutenberg #37319(​https://github.com/WordPress/gutenberg/issues/37319).

If I set the hierarchical and show_count of wp_list_categories or wp_dropdown_categories to true, the counts for some categories aren't displayed correctly when there are posts that have grandchild categories.

Example:

---

wp_list_categories( array( 'show_count' => true, 'hierarchical' => true ) );

• Parent (4)
  • Child 1 (3)
    • Grandchild 1 (1)
  • Child 2 (1)

---

wp_list_categories( array( 'show_count' => true, 'hierarchical' => false ) );

• Child 1 (2)
• Child 2 (1)
• Grandchild 1 (1)

---

"Child 1" category counts are different, but the second data (hierarchical is false) is correct in my test data.
For some reason, I think the number of grandchild categories is counted as well.

This problem is the same when I output with wp_dropdown_categories.