Impact on item Price change on the cost accounting line creation

Hello,

We have situation where a sales order / billing created for Dec 2019 and the revenue  accounting line entries were posted in Dec 2019 as well. However suddenly in Aug 2020, the expense accounting lines were created for the same Sales order / billing. This happened for a few specific items. What would cause this?  It appears these entries were created by "Create Cost Accounting Lines entries AE Process CM_COST". in what possible scenario this might occur. We are trying narrow down the problem and appreciate if anyone can provide some insights on this

Thanks, Nav