Shipping Webhook Response: userDefinedId not being set on order completion

Since October 2nd, 2023, with no code changes to our backend webhook processor, we have experienced issues with Shipping webhook responses no longer setting the userDefinedId on a completed order. This used to be set automatically but something changed with Snipcart that fails to process or set this properly on order completion.

Were there any updates to Snipcart that could have affected this?