You won't get a defect if you open a cancel transaction at the buyer's request - just be careful when selecting the reason for cancellation (ie use "buyer changed mind" option)

Ebay has list of resons when it is ok to cancel a transaction and not receive a defect.  The reason for receiving a defect is:

• Transaction cancellation by the seller when the item was out of stock, or sold to another buyer

If a UPI case is closed without payment, the buyer receives a UPI strike and CANNOT leave feedback.