Ratelimit service is not working properly, misbehaving while flushing

[mks27]

Hi Team, I have implemented Istio global rate-limiting using the rate-limit service and redis service provided by envoy.
I have observed following issues in the rate-limit service.

1. when the rate-limit service are flushing counters and gauge, my requests are crossing rate-limiting threshold but they are not getting 429. These requests are also not reported in rate-limit service logs. after some requests ,ratelimiting starts working properly.
2. when the rate-limit threshold has been reached for the requested URL, getting 429 but some hits are reaching to the respected service and not giving 429.

I am using below images -
ratelimit - envoyproxy/ratelimit:4c088856
redis - redis:6.2.11-alpine

This is my ratelimit-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ratelimit
  namespace: istio-iut
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ratelimit
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: ratelimit
    spec:
      containers:
      - image: envoyproxy/ratelimit:4c088856
        imagePullPolicy: Always
        name: ratelimit
        command: ["/bin/ratelimit"]
        env:
        - name: LOG_LEVEL
          value: debug
        - name: REDIS_SOCKET_TYPE
          value: tcp
        - name: REDIS_URL
          value: redis:6379
        - name: USE_STATSD
          value: "false"
        - name: RUNTIME_ROOT
          value: /data
        - name: RUNTIME_SUBDIRECTORY
          value: ratelimit
        - name: RUNTIME_WATCH_ROOT
          value: "false"
        - name: RUNTIME_IGNOREDOTFILES
          value: "true"
        - name: MERGE_DOMAIN_CONFIG
          value: "true"
        - name: HOST
          value: "::"
        - name: GRPC_HOST
          value: "::"
        ports:
        - containerPort: 8080
        - containerPort: 8081
        - containerPort: 6070
        volumeMounts:
        - name: config-volume
          mountPath: /data/ratelimit/config
      volumes:
      - name: config-volume
        projected:
          sources:
          - configMap:
              name: ratelimit-config-api1
          - configMap:
              name: ratelimit-config-api2

This is my redis-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: istio-iut
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - image: redis:6.2.11-alpine
        imagePullPolicy: Always
        name: redis
        ports:
        - name: redis
          containerPort: 6379
      restartPolicy: Always
      serviceAccountName: ""

Please let me know , what is the reason behind this behavior.