The error message. looks like no data on that endpoint. How about executing it from the command line with --debug and --verbose ?
If I execute it from my command line on our test on-prem cluster on 1.21, it looks like this:
$ kubectl get --raw /api/v1/nodes/k8-w1/proxy/healthz -v=9
I0602 08:10:34.950619 3643313 loader.go:372] Config loaded from file: /root/.kube/config
I0602 08:10:34.951341 3643313 round_trippers.go:435] curl -k -v -XGET -H “Accept: application/json, /” -H “User-Agent: kubectl/v1.21.7 (linux/amd64) kubernetes/1f86634” ‘https://1.2.3.4:6443/api/v1/nodes/k8-w1/proxy/healthz’
I0602 08:10:34.983233 3643313 round_trippers.go:454] GET https://1.2.3.4:6443/api/v1/nodes/k8-w1/proxy/healthz 200 OK in 31 milliseconds
I0602 08:10:34.983257 3643313 round_trippers.go:460] Response Headers:
I0602 08:10:34.983267 3643313 round_trippers.go:463] Content-Type: text/plain; charset=utf-8
I0602 08:10:34.983271 3643313 round_trippers.go:463] Date: Thu, 02 Jun 2022 06:10:34 GMT
I0602 08:10:34.983274 3643313 round_trippers.go:463] X-Content-Type-Options: nosniff
I0602 08:10:34.983276 3643313 round_trippers.go:463] Content-Length: 2
I0602 08:10:34.983279 3643313 round_trippers.go:463] Cache-Control: no-cache, private