tls-server-name is missing when using oc client causing x509: certificate signed by unknown authority. Here is PR https://github.com/openshift/oc/issues/1457. 

Please use this slack thread for any reference. 
https://redhat-internal.slack.com/archives/CKJR6200N/p1689170150899359

A kubeconfig might look like this:apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tLS1CRUdJ.......<redacted>....
    server: https://celonis.teleport.sh:443
    tls-server-name: kube-teleport-proxy-alpn.celonis.teleport.sh
  name: celonis.teleport.sh
contexts:
- context:
    cluster: celonis.teleport.sh
    user: celonis.teleport.sh-<cluster_name>
  name: celonis.teleport.sh-<cluster_name>
current-context: celonis.teleport.sh-<cluster_name>When running oc commands against the default namespace these commands succeed:oc get pods
No resources found in default namespace.
When running the oc project <namespace> command this modifies the context and sets the namespace. When this operation occurs the tls-server-name attribute is not obeyed which then causes an x509$oc project <namespace>
Now using project "<namespace>" on server "https://celonis.teleport.sh:443".
$oc get pods --loglevel 8
I0613 12:41:05.038351  122971 loader.go:373] Config loaded from file:  /home/kwoodson/.kube/config
I0613 12:41:05.046716  122971 round_trippers.go:463] GET https://celonis.teleport.sh:443/api/v1/namespaces/<namespace>/pods?limit=500
I0613 12:41:05.046732  122971 round_trippers.go:469] Request Headers:
I0613 12:41:05.046741  122971 round_trippers.go:473]     User-Agent: oc/4.13.0 (linux/amd64) kubernetes/92b1a3d
I0613 12:41:05.046746  122971 round_trippers.go:473]     Accept: application/json;as=Table;v=v1;g=meta.k8s.io,application/json;as=Table;v=v1beta1;g=meta.k8s.io,application/json
I0613 12:41:05.121700  122971 round_trippers.go:574] Response Status:  in 74 milliseconds
I0613 12:41:05.121716  122971 round_trippers.go:577] Response Headers:
I0613 12:41:05.121787  122971 helpers.go:264] Connection error: Get https://celonis.teleport.sh:443/api/v1/namespaces/<namespace>/pods?limit=500: x509: certificate signed by unknown authority
Unable to connect to the server: x509: certificate signed by unknown authority
If we review the kubeconfig we can see a new context was added as well as a new server:apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: <redacted>
    server: https://celonis.teleport.sh:443
  name: celonis-teleport-sh:443
- cluster:
    certificate-authority-data: <redacted>
    server: https://celonis.teleport.sh:443
    tls-server-name: kube-teleport-proxy-alpn.celonis.teleport.sh
  name: celonis.teleport.sh
contexts:
- context:
    cluster: celonis.teleport.sh
    user: celonis.teleport.sh-<namespace>
  name: celonis.teleport.sh-<namespace>
- context:
    cluster: celonis-teleport-sh:443
    namespace: <namespace>
    user: kwoodson/celonis-teleport-sh:443
  name: <namespace>/celonis-teleport-sh:443/kwoodson
current-context: <namespace>/celonis-teleport-sh:443/kwoodson
As we can see the tls-server-name attribute in this context was not copied to the new context. If I copy this attribute from the old cluster to the new cluster this works.