An Apex trigger creates an order co record every time an Opportunity is won by...

Disable all flows, and then re-enable them one at at time to see which one causes the error.

Run the Apex Test Classes for the Apex trigger to ensure the code still has sufficient code coverage.

Set up debug logging for every Sales Rep, then monitor the logs for errors and exceptions,

Add system.debug() statements to the code and use the Developer Console logs to trace the code.