multus default-route parameter not working in 4.12 [4.13]

---
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
  name: bridge-conf
spec:
  config: '{
    "cniVersion": "0.3.0",
    "type": "bridge",
    "ipam": {
        "type": "whereabouts",
        "ipRanges": [
            {
                "range": "192.168.12.0/24",
                "range_start": "192.168.12.50",
                "range_end": "192.168.12.100"
            },
            {
                "range": "2001:db8::/32"
            }
        ]
    }
  }'
---
apiVersion: v1
kind: Pod
metadata:
  name: samplepod
  annotations:
    k8s.v1.cni.cncf.io/networks: '[{"interface":"test0","name":"bridge-conf", "default-route": ["192.168.12.254", "2001:db8::ff"]}]'
spec:
  containers:
  - name: samplepod
    command: ["/bin/ash", "-c", "trap : TERM INT; sleep infinity & wait"]
    image: alpine

$ oc version | grep -i server
Server Version: 4.12.0-0.ci-2023-10-25-074812

$ oc exec -it samplepod -- ip route
10.128.0.0/14 via 10.131.0.1 dev eth0 
10.131.0.0/23 dev eth0 scope link  src 10.131.0.23 
172.30.0.0/16 via 10.131.0.1 dev eth0 
192.168.12.0/24 dev test0 scope link  src 192.168.12.50 

$ oc exec -it samplepod -- ip -6 route
2001:db8::/32 dev test0  metric 256 
fe80::/64 dev eth0  metric 256 
fe80::/64 dev test0  metric 256 
multicast ff00::/8 dev eth0  metric 256 
multicast ff00::/8 dev test0  metric 256 

should contain: default via ...