Creating seperate PDF document for completely refunded orders

Hey,

I occasionally have the case that customers refund the entire order. As soon as the refund is executed, there will be generated a wp_post which can be seen in the order details:

Rückerstattung #38275 – 19. April 2024, 14:24 von?Admin Bestellung vollst?ndig erstattet.

I wanna automatically create a PDF invoice document referring to this complete refund. I can already achieve this by manually entering

“https://www.mywebsite.de/wp-admin/admin-ajax.php?action=generate_wpo_wcpdf&document_type=invoice&order_ids=38275&access_key=abcdefg”

into my browser bar. Please note: 38275 is the ID of the refund, not the parent order! How can I automatically create this document (or even attach it to the refund order mail) as soon as an order goes from “on-hold” to “refunded”?