To get the data source used and referenced to answer questions in Copilot Studio, you can utilize the knowledge sources configured in Copilot Studio. When you set up your Copilot, you can select various knowledge sources such as public websites, SharePoint, Dataverse, and file uploads. Each of these sources can provide the necessary URLs for the content used in the answers.
In your Power Automate flow, you can configure it to collect the relevant data from the Conversation Transcript table, but since it doesn't record Teams and Microsoft 365 Copilot conversations, you may need to create a custom page or a custom logging mechanism to capture this information. Make sure to include the ContentLocation property in your custom data setup, which can hold the URL for the citation of the source content.
By doing this, you will be able to track the knowledge URLs used in the answers generated by Copilot Studio.