QuickBooks Online has partnered with hundreds of apps that offer a variety of add-on services, vendor.bi432.
Please note that the integration between DecoNetwrok and QBO is one way. It means that order data is pushed from DecoNetwork into the accounting software and not vice versa.
In this case, I would recommend reaching out to DecoNetwork. They can take a closer look at this to figure out why the purchase orders aren't syncing in QBO.
Additionally, I would like to share some articles that can provide further guidance on managing third-party apps in QuickBooks Online:
Feel free to reach out to us in the Community if you require further assistance when recording transactions in the program. The QuickBooks Team is always available to provide guidance whenever you need it.