We see a strange behavior in Draft Orders API (2022-01). If we just update draft order tags via API, it removes all the discounts added in that draft order.
Same thing happens if we add/update shipping line. This issue we started facing since last 2 days.
We are also facing same issue while using update Draft Order Rest API. Seems something is changed in Shopify Rest API. Were you able to figure any workaround for this?