This article explains the Hardware Compatibility - Network(RDMA NIC: RoCE v2) is vSAN certified check in the vSAN Health Service and provides details about why it might report an error.
VMware vSAN 8.0U3 and higher
This health check checks whether the RDMA NICs used in the vSAN cluster are certified and the current vSAN configuration is also certified for the RDMA NICs by the Broadcom Compatibility Guide (VCG).
Note: This check is only applicable when RDMA is enabled on the vSAN cluster.
It means that the RDMA NIC is not certified or the current vSAN configuration is not certified for the RDMA NIC by the Broadcom Compatibility Guide (VCG).