GoAffPro provides you with the option to disable the commission that is calculated on tips.
To disable the commission that is calculated on tips, go to the Commission Modifiers section in the Commissions tab of the GoAffPro admin panel.
Here, click on Add new modifier.
Now, select the "Product Name" rule.
After this, set the "matches" value to Tip.
Now, set the "adjust commission by" percentage to -100%.
Finally, click on Add Modifier.
The newly set commission modifier will prevent the commission from being calculated on the tip.