A quick one to automatically uncheck the “Restock refunded items” in the WooCommerce Order Admin by default. Doing this can save a few human errors in certain circumsances.

Simply add this to your functions or plugin file

add_filter('woocommerce_restock_refunded_items', '__return_false');

 

Refs:

https://github.com/woocommerce/woocommerce/pull/21314
https://ivetetecedor.com/how-to-disable-woocommerce-restock-refunded/