Why is Google search console throwing an error?

Question

XML

Your Sitemap or Sitemap index file does not properly declare the namespace.

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd http://www.w3.org/TR/xhtml11/xhtml11_schema.html http://www.w3.org/2002/08/xhtml/xhtml1-strict.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/TR/xhtml11/xhtml11_schema.html">
    <url>
        <loc>https://example.com/</loc>
        <xhtml:link rel="alternate" hreflang="en" href="https://example.com/en/"/>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.com/ru/"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>1.00</priority>
    </url>
    <url>
        <loc>https://example.com/en/reset-password</loc>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.com/ru/reset-password"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/reset-password"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>0.80</priority>
    </url>
    <url>
        <loc>https://example.com/en/sign-up</loc>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.com/ru/sign-up"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/sign-up"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>0.80</priority>
    </url>
    <url>
        <loc>https://example.com/en/terms-and-conditions</loc>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.com/ru/terms-and-conditions"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/terms-and-conditions"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>0.80</priority>
    </url>
    <url>
        <loc>https://example.com/en/privacy-policy</loc>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.com/ru/privacy-policy"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/privacy-policy"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>0.80</priority>
    </url>
    <url>
        <loc>https://example.com/en/contact-us</loc>
        <xhtml:link rel="alternate" hreflang="ru" href="https://example.comrucontact-us"/>
        <xhtml:link rel="alternate" hreflang="hy" href="https://example.com/hy/contact-us"/>
        <lastmod>2021-08-20T06:31:17+00:00</lastmod>
        <priority>0.80</priority>
    </url>
</urlset>