‘Sitemap appears to be an HTML page’ error in Google console while adding sitemap URL

Question:  I entered the sitemap URL into Google console, and it is saying Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead. How do I send the correct format to them?
Answer: You may see this error while adding the sitemap URL as sitename.chi.v6.pressero.com/sitemap
Instead, we need to add the URL in Google console for XML file as sitename.chi.v6.pressero.com/sitemap.xml
The first URL is for the end-users whereas the other one (XML format) is for integrations like Google.