The Net Revenue of all items that were refunded.
Formula
Refund Value = SUMIF( Gross Revenue - Taxes, Payment Status = "Refunded")
Refund Rate = Refund Value / Gross Revenue
Explanation
Refunds are equal to the Gross Revenue after Taxes of all items with the Payment Status "Refunded".
Klar associates the return to the date the order was placed, while Shopify to the day the return was logged.
So if an order is placed on the 5th of May and returned on the 15th of May, Klar will set the return value on the 5th of May whereas Shopify will set it on the 15th.
Notes
n/a