Your on-premises data center has two routers connected to your Google Cloud environment via separate VPNs (one per router). All applications are functioning correctly, but traffic is only flowing through a single VPN instead of being load-balanced across both connections as intended.

During troubleshooting, you observe the following:

• Each on-premises router is configured with a unique ASN.
• Each on-premises router has identical routes and priorities configured.
• Both on-premises routers are connected via VPN to a single Cloud Router.
• BGP sessions are established between both on-premises routers and the Cloud Router.
• Only one on-premises router's routes appear in the routing table.

What is the most likely cause of this issue?