Hello @Casey Moore , I got a response back from the team. The server variables are only supported by Azure Front Door Standard/Premium. To implement the redirection scenario above to pass the {request_uri}
server variable as a query parameter you will have to switch to Azure Front Door Standard/Premium. As this limitation was not highlighted in the documentation you referred. I have created this document feedback item in order to add a note on this limitation to the document.
Please let me know if you have any additional questions. Thank you!