I have testimonials pages on my website. The testimonials are collections page. I’ve enabled the option to exclude them from the sitemap, HOWEVER, the individual testimonials are still present in the sitemap, as well as are missing a noindex tag.
If you want to block pages or collection pages from being indexed in search engines you need to handle that yourself. The indexing Webflow is talking about (option in page settings) is the internal search engine used when you implement search on your site.