Shopify Merchant dashboards have a recent notification referring to changes in the calculation of the Average Order Value that reads:
"Previously, the definition of Average Order Value (AOV) in Shopify Analytics was based on the "total sales" value of an order. To better match merchant expectations, this definition has been adjusted to be based on an order's value of "gross sales minus discounts", excluding any adjustments made to the order after it was created. This adjusted definition of AOV applies to all places where AOV is shown within the Admin, including historical data."
This change is significant to understand how AOV varies with promotions and sales and gives merchants more accurate performance analytics for better decision-making.