When we create new order using API, Shopify sends order confirmation to the customer - despite flag send_receipt is not set (defaults to false).
One specific to the API call is that we copy the order name of some existing order + adding some suffix, so the both orders has the same number. But we are creating the JSON data from scratch, not reusing the existing order JSON
The operation is basically to “edit” already paid order
Did you see this note in the api docs? Sound like it relates to you?
If you’re working on a private app and order confirmations are still being sent to the customer when send_receipt is set to false, then you need to disable the Storefront API from the private app’s page in the Shopify admin.