Why do Vendor Credits show up on the A/P Aging Detail report?

Good morning, @office-gsamarill.

Thanks for reaching out to the QuickBooks Community. I hope you're having a great day so far. 

An A/P aging report includes vendor credits, vendor bills, and invoice payments. It categorizes these transactions by how long ago the invoice date was, and highlights the total amounts that are due or overdue.

In short, the due date for a vendor credit is the same as the credit date, which is the date the credit was issued. The bill currency opening balance shows the amount of the credit as of the “Age As Of” date on the report.

I hope this explanation helps. If you have any additional questions or concerns, please don't hesitate to let me know. 

In case you may need it in the future, you can learn more about customizing your reports in: Customize Reports in QuickBooks Online. 

I'm always around to the lend a hand. Have a good one!