API - "User Reason" field

We are currently working on creating a Power BI (PBI) report to capture the details of On-demand feature usage. Everything has been configured and is functioning as expected. In the existing PBI report, we would like to include the "User Reason" field. However, we are unable to identify the exact API that provides the "User Reason" field data. Could you please guide us on how to retrieve this information via API?