Hi there, I’ve been seeing the same thing for the past three or four weeks now.
Yoast has added multiple empty submenu items with this markup:
<li class="wp-has-submenu wp-not-current-submenu"><a href="admin.php?page=wpseo_installation_successful_free" class="wp-has-submenu wp-not-current-submenu" aria-haspopup="true"><div class="wp-menu-arrow"><div></div></div><div class="wp-menu-image dashicons-before" aria-hidden="true"></div><div class="wp-menu-name"></div></a>
<ul class="wp-submenu wp-submenu-wrap"><li class="wp-submenu-head" aria-hidden="true"></li><li class="wp-first-item current"><a href="admin.php?page=wpseo_installation_successful_free" class="wp-first-item current" aria-current="page"></a></li><li><a href="admin.php?page=wpseo_configurator"></a></li></ul></li>
When you click the empty link, it takes you to a page telling you that “You’ve successfully installed Yoast SEO!”
ImgBB photo links:
Empty Yoast submenu links: https://ibb.co/PrnK3yp
Successful install page: https://ibb.co/rwZFtcL
