turn_off_switching_per_product

turn_off_switching_per_product.php

<?php
add_filter('woocommerce_subscriptions_can_item_be_switched','turn_off_switching_per_product', 10, 3);
function turn_off_switching_per_product(){
  $turn_off_switching_for_these_products = array(10,24,438); // change this for whatever products you want to make not switchable
  $product_id = wcs_get_canonical_product_id( $item );
  if (in_array($product_id, $turn_off_switching_for_these_products)) {
    $item_can_be_switch = false;
  }
}