Notices are render inside sub-menu’s content

I develop a plugin but I’ve got a problem when I render sub-menus (added with the hook admin_menu). At the moment of the callback, I render the content with the following:

But I don’t know why they are render inside the same content (see attachment).
enter image description here
I’m using PHP/MySQL 7.4.2 with theme Sydney Pro in localhost

Thanks in advance