kubectl error: x509: certificate signed by unknown authority - kubernetes

Question

Friends, I'm new to Kubernetes and recently installed Kubernetes manually through a tutorial,execute the command:kubectl exec -it -n kube-system coredns-867b8c5ddf-8xfz6 -- sh,an error occurred: "x509: certificate signed by unknown authority",kubectl log command will also report the same error,but kubectl get nodes and kubectl get podes can get node information normally,This is the step for me to configure RBAC authorization to allow the kube-api server to access the kubelet API on each worker node:
cat <<EOF | kubectl apply --kubeconfig admin.kubeconfig -f -
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
labels:
kubernetes.io/bootstrapping: rbac-defaults
name: system:kube-apiserver-to-kubelet
rules:
- apiGroups:
- ""
resources:
- nodes/proxy
- nodes/stats
- nodes/log
- nodes/spec
- nodes/metrics
verbs:
- "*"
EOF
cat <<EOF | kubectl apply --kubeconfig admin.kubeconfig -f -
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: system:kube-apiserver
namespace: ""
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:kube-apiserver-to-kubelet
subjects:
- apiGroup: rbac.authorization.k8s.io
kind: User
name: kubernetes
EOF
This is admin.kubeconfig content:
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: LS0t******tLQo=
server: https://127.0.0.1:6443
name: kubernetes
contexts:
- context:
cluster: kubernetes
user: admin
name: default
current-context: default
kind: Config
preferences: {}
users:
- name: admin
user:
client-certificate-data: LS0t******Cg==
client-key-data: LS0tL******LQo=
The content in "~/.kube/config" is the same as the content in admin.kubeconfig. I went to check and confirmed that my certificate has not expired. It seems that the Token authentication of the dashboard is also affected by this problem and cannot pass,my system's CentOS7.7. The kubernetes component version is 1.22.4. I hope to get help.