Sub–subcategories not showing in sitemap on specific websites (works only on default store view)

We are running a Magento 2 multi-website setup. On our default store view, the XML sitemap is generated correctly and includes all categories, including sub–subcategories.

However, for some of our other websites, certain sub–subcategories are missing from the generated sitemap. The categories exist in the admin panel, are active, have URL keys, and appear properly in the frontend navigation. But they are not included in the sitemap for those specific websites.

Has anyone faced this issue before, or is there something specific in Magento’s multi-store sitemap logic that could cause sub–subcategories to be excluded?

www.gardenlux.nl  one of our website that have not generated the sub categories sitemap url

Any guidance on debugging or known fixes would be helpful.