don't autocomplete any orders

dont_autocomplete.php

<?php

add_filter( 'woocommerce_payment_complete_order_status', 'my_function', 100, 3 );

function my_function( $new_order_status, $order_id, $order = null ) {

if ( $new_order_status == 'completed' ) {
  $new_order_status = 'processing';
}
  
return $new_order_status;

}