Hallo Forum. How do I set all categories that are set to noindex to index?

I also wanted to ask about this noindex feature. Is there any reason to exclude the pages from being indexed by search engines? Google seems to complain about it.

If in the category is empty the search page will be set noindex but if there are ads will be set on index.

Thank you for your answer.

Empty category return 404 code.

Thank you Mb-Themes