Aloha, we noticed that WordPress 5.5 introduced a new method of user enumeration in the sitemap feature intended to help search engines index site content:

New XML Sitemaps Functionality in WordPress 5.5

If you visit /wp-sitemap.xml on any WordPress site, you should see /wp-sitemap-users-1.xml as a link that will list all site users with their /author/username link. These do still appear with this plugin installed and activated.

Looks like the easiest way to remove that is to hook into wp_sitemaps_add_provider. Would be excellent if you could integrate that into this plugin!

Example (from the link above):

add_filter(
    'wp_sitemaps_add_provider',
    function( $provider, $name ) {
        if ( 'users' === $name ) {
            return false;
        }
 
        return $provider;
    },
    10,
    2
);