This example workload shows an Azure Virtual WAN deployment with multiple hubs per region. To improve availability and scalability, each hub peers to geographically dispersed, redundant Azure ExpressRoute circuits. This architecture is for exceptionally large and critical workloads. It supports business units and applications that reside on spoke virtual networks. The spoke virtual networks often have security requirements for internet-to-spoke or spoke-to-spoke connectivity.

https://learn.microsoft.com/en-us/azure/architecture/networking/architecture/massive-scale-azure-architecture