Error displaying Yoast WordPress SEO

I am using Yoast WordPress SEO on all my WordPress site. One the one I am getting the following error:

This XML file does not appear to have any style information associated with it. The document tree is shown below.

https://regenesysfoundation.org/sitemap_index.xml

Please help me, I am not sure what is wrong

https://www.ads-software.com/plugins/wordpress-seo/