KEDA not scaling pods based on RabbitMQ queue length

I'm trying to use KEDA to auto-scale a Celery worker pod based on the current length of a RabbitMQ message queue. The worker runs as expected, however, it is not scaling under load.

For reference, I'm using KEDA v2.7.1.

Logs from keda-operator pod:

1.6569289126033094e+09  ERROR   controller.scaledobject Reconciler error        {"reconciler group": "keda.sh", "reconciler kind": "ScaledObject", "name": "celery-worker-scaler", "namespace": "default", "error": "error establishing rabbitmq connection: dial tcp: lookup rabbitmq on 10.96.0.10:53: server misbehaving"}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem
        /go/pkg/mod/sigs.k8s.io/controller-runtime@v0.11.2/pkg/internal/controller/controller.go:266
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2
        /go/pkg/mod/sigs.k8s.io/controller-runtime@v0.11.2/pkg/internal/controller/controller.go:227

Clearly there is some issue with connecting to the rabbitmq pod

keda.yaml:

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: celery-worker-scaler
  namespace: default
spec:
  scaleTargetRef:
    name: celery-worker
  pollingInterval: 3
  minReplicaCount: 1
  maxReplicaCount: 10
  triggers:
    - type: rabbitmq
      metadata:
        host: amqp://guest:guest@rabbitmq:5672
        protocol: amqp
        queueName: celery
        mode: QueueLength
        value: "5"

rabbitmq.yaml:

# deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: rabbitmq
  labels:
    app: rabbitmq
spec:
  replicas: 1
  selector:
    matchLabels:
      app: rabbitmq
  template:
    metadata:
      labels:
        app: rabbitmq
    spec:
      containers:
      - name: rabbitmq
        image: rabbitmq:management
        env:
          - name: RABBITMQ_DEFAULT_USER
            valueFrom:
              secretKeyRef:
                name: secret
                key: rabbitmq-user
          - name: RABBITMQ_DEFAULT_PASS
            valueFrom:
              secretKeyRef:
                name: secret
                key: rabbitmq-password
        ports:
        - containerPort: 15672
          name: management
        - containerPort: 5672
          name: rabbitmq
---
# service
apiVersion: v1
kind: Service
metadata:
  name: rabbitmq
  labels:
    app: rabbitmq
spec:
  selector:
    app: rabbitmq
  ports:
  - port: 5672
    name: rabbitmq
    targetPort: rabbitmq
    protocol: TCP
  - port: 15672
    name: rabbitmq-mgmt
    targetPort: management

The keda.yaml file is applied in the keda namespace (even though I wrote default at the top). Since my rabbitmq pod is in the default namespace, I had to set the host as follows: amqp://guest:guest@rabbitmq.default:5672