Kubernetes plugins upgrade for kubernetes > 1.18?

I ran into the same issue, after some digging through the code I found this by adding some debug output into /omd/sites/twa/lib/python/kubernetes/client/rest.py:231

OMD[twa]:~$ /omd/sites/twa/share/check_mk/agents/special/agent_kubernetes '--token' '<token>' '--infos' 'services,deployments,pods,daemon_sets,stateful_sets' '--port' '443' '--no-cert-check' '--url-prefix' 'https://<URL>' '--path-prefix' '/k8s/clusters/c-c7fcd' --debug '<HOST>'
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/apis/storage.k8s.io/v1/storageclasses')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/api/v1/namespaces')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/apis/rbac.authorization.k8s.io/v1/roles')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/apis/rbac.authorization.k8s.io/v1/clusterroles')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/api/v1/componentstatuses')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/api/v1/nodes')
('URL: ', 'https://<URL>:443/k8s/clusters/c-c7fcd/api/v1/nodes/shared-cluster-node-1/proxy/stats')
kubernetes.client.rest.ApiException: (404)
...

so it’s actually the request to get stats for the node which leads to a 404.
I can’t find anything in the k8s API docs which describes this endpoint and I also have no clue which might be missing in my cluster to serve this endpoint.

Update:
found this issue here in the forum, which provides a workaround:
Deprecated cadvisor stats with Kubernetes 1.18 and check-mk 1.6.0p18