ARP Broadcast requests on LAN components on WAN Disconnection

We have a newly implemented L2/L3 Multipath Network Infrastructure setup (by a third party) at our facilities. We are trying to validate the setup. All the data from Building A is sent to Building C via Building B (Building B is like a datacenter). When we disconnect Building C (stress test by unplugging Building C and disrupting the path) all the LAN components on Building A network lose connectivity. We took wireshark logs on a computer on Building A and found that when we lose the connectivity to Building C, there is a ARP broadcast storm querying about the LAN components on Building A (which is weird, as they should all be talking to each other on the local network) There are no responses from any components from the devices.

I am happy to share the wireshark logs and the network diagram.

Thank you for your support