Orderby ASC changes to DESC in WP_Query

You’ve made “orderby” and “order” part of the date_query sub-array. “Order” parameters belong to the main parameters array.

I can’t vouch for the part of your code that concerns the year and the above-undefined variable $ppy, but if you want the posts from a specified year in ascending order by ‘post_date’ (which is the default), you’d try:

$args = array( 
        'date_query' => array(
                     'year' => $ppy,
         ),
         'order'   => 'ASC',
);

You can leave off ‘post_date’, since it’s the default, but it doesn’t hurt to specify if you’ve got a lot else going on that may potentially change the query.