Broken sitemap url

Hello,

I have a problem with the sitemap url.
In the sitemap_index.xml file, the HTTPS is missing in the url <?xml version=”1.0″ encoding=”UTF-8″?><?xml-stylesheet type=”text/xsl” href=”//infraviacapital.com/wp-content/plugins/wordpress-seo/css/main-sitemap.xsl”?>

Can you tell me how to fix this bug?

Thank you so much !

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