What is generating my meta og:description?

The Facebook Page Publish plugin is adding the og:description. Looking through the code in fpp_index.php at lines 843 – 851:

    $description = array();
    if ($options['show_post_author']) {
            $description[] = esc_attr(fpp_get_post_author($post));/*, ENT_COMPAT, 'UTF-8')*/
    }
    if ($options['show_post_categories']) {
            $categories = esc_attr(fpp_get_post_categories($post));/*, ENT_COMPAT, 'UTF-8')*/
            if (!empty($categories)) $description[] = $categories;
    }
    echo '<meta property="og:description" content="'.implode(' | ', $description).'"/>';

It appears that you have only checked the “post categories” option and have unchecked “post author” on the plugin admin page. See this screenshot.

That’s the option the plugin is using the generate the og:description.