The wpmu_blogs_columns filter is not working

Question

I want to add an additional column in the multisite Sites page (sites.php). Found this code on this SO:

add_filter('wpmu_blogs_columns', 'xx_add_expired_date_column');

function xx_add_expired_date_column($site_columns) {
    $site_columns['expired_Date'] = 'Expires';
    return $site_columns;
}

/* Populate site_name with blogs site_name */
add_action('manage_sites_custom_column', 'xx_exipred_date_data', 10, 2);

function xx_exipred_date_data($column_name, $blog_id) {
    $current_blog_details = get_blog_details(array('blog_id' => $blog_id));
    echo ucwords($current_blog_details->blogname);
}

The wpmu_blogs_columns filter should add the additional column on the Sites screen. I put this code in a plugin I am developing. Other functions of that plugin are working properly. The plugin has been network activated.

When I look at the Sites list (Network Admin, Sites, or via the Network dashboard Sites, All Sites), the extra column is not there.

If I put a die() statement after the xx_add_expired_date_column function, that 'die' never happens.

I think it may be a loading sequence error - maybe the plugin is not being loaded on the Sites page? What can be done to enable this additional column?

Added 7 Feb 2023

Further testing: the wpmu_blogs_columns filter will work in the theme's (or Child Theme's) functions.php file, but not in a plugin.

Added 8 Feb 2023

As mentioned in the soon-to-be-accepted answer, the column array is $sites_columns (plural 'sites'). And the $column_name is important. The code in the answer will work.

Answer 1

I tested your code, fixing the $colum_name issue and it works ok for me.

add_filter('wpmu_blogs_columns', function ($site_columns) {
    $site_columns['expired_Date'] = 'Expires';
    return $site_columns;
});

add_action('manage_sites_custom_column', function ($column_name, $blog_id) {
    if ( 'expired_Date' === $column_name ){
        $current_blog_details = get_blog_details(array('blog_id' => $blog_id));
        // do_action( 'qm/debug', ['Details:', $current_blog_details ] );
        echo ucwords($current_blog_details->last_updated);
    }
}, 10, 2);

You have to check the $column_name otherwise the echo will print in all custom columns.

Both the filter and the action are pretty specific, they will only run on the page /wp-admin/network/sites.php and nowhere else.
I tried the code above using Snippets plugin and also as a mu-plugin and both worked the same, haven't tried as a plugin (maybe you can wrap everything inside a add_action('plugins_loaded', function(){}); hook).

The qm/debug is for the plugin Query Monitor, a must-have for WP devs :)