Route Server is Virtual WAN Routing-lite with BGP only  option brought to Virtual Networks

Azure Route Server

https://docs.microsoft.com/en-us/azure/route-server/overview

https://journeyofthegeek.com/2021/11/11/a-deep-dive-into-azure-route-server/

Multi-region networking with Azure Route Server

https://learn.microsoft.com/en-us/azure/route-server/multiregion