We use simple services procurement for our service Purchase Orders (POs) or service PO-based invoicing without Service Entry Sheets (SES), and we do not want exceptions such as PO Quantity Variance or PO Received Quantity Variance on our service invoices.
Even if try to prevent this by unchecking the Service PO option in Refine invoice source by condition for those exception types, the exceptions still show up on the associated Invoice Reconciliation (IR) document.
How can we stop these exceptions from firing on service invoices?

Have your Designated Support Contact (DSC) file a Case to do the following:

• Enable the feature toggle SINV-11655 (Apply service order invoice exception types to non-SES service orders)

Then, in the exception type configuration, under Refine invoice source by condition, ensure that Service PO is unchecked for the exceptions that you do not want to see on any service invoices.
On the other hand, if you do want an exception to fire on service invoices, ensure that Service PO is checked instead.

Invoicing > Invoice Reconciliation > Invoice Reconciliation Exceptions
Invoicing > Service Invoicing