Namespaced crd middleware "does not exist"

Traefik Traefik v2 (latest)
1

I am installing Traefik with Helm (Chart version 10.1.2) and added a crd middleware, which I setup for both the web and websecure entrypoint. When starting the pod, I got following two errors:

...
time="2021-08-10T22:41:05Z" level=error msg="middleware \"kube-system-security-headers@kubernetescrd\" does not exist" entryPointName=web routerName=web-to-443@internal
...
time="2021-08-10T22:41:06Z" level=error msg="middleware \"kube-system-security-headers@kubernetescrd\" does not exist" entryPointName=web routerName=web-to-443@internal

When calling https sites from my deployment, I see that the middleware works, as it modifys http headers as expected. But I would like to know if there is something wrong with the configuration and if somethings might not work as expected.

The (shortened) K8s deployment object looks like following:

apiVersion: apps/v1
kind: Deployment
...
spec:
  ...
  template:
    ...
    spec:
      containers:
      - args:
        - --entryPoints.web.address=:8000/tcp
        - --entryPoints.websecure.address=:8443/tcp
        - --entrypoints.web.http.redirections.entryPoint.to=:443
        - --entrypoints.web.http.redirections.entryPoint.scheme=https
        - --entrypoints.websecure.http.tls=true
	...
        - --entrypoints.websecure.http.tls.options=kube-system-secure-tls-options@kubernetescrd
        - --entrypoints.web.http.middlewares=kube-system-security-headers@kubernetescrd
        - --entrypoints.websecure.http.middlewares=kube-system-security-headers@kubernetescrd
        image: traefik:2.4.13
	...

The K8s middleware object looks like following:

apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: security-headers
  namespace: kube-system
spec:
  headers:
    browserXssFilter: true
    contentTypeNosniff: true
    customResponseHeaders:
      Server: ""
      X-Frame-Options: sameorigin
      X-Powered-By: ""
      mxfvor: vefer
    forceSTSHeader: true
    sslRedirect: true
    stsIncludeSubdomains: true
    stsPreload: true
    stsSeconds: 315360000

Is there a reason for the error output in the logs?