Hi Quirin, thanks for asking, that’s a great question. Can you install my Store Toolkit for WooCommerce Plugin then locate an Order where a now deleted Coupon has been assigned. You will see what Post meta and Order Item meta is linked to that Order within the Edit Order screen of the WordPress Administration.
https://wordpress.org/plugins/woocommerce-store-toolkit/
If the data is intact and hasn’t been deleted by a WooCommerce cleanup process then we can export it and/or filter Order exports by it 🙂
