The etcd CA certificate is valid for 5 years instead of 10 years.

https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/security_and_compliance/certificate-types-and-descriptions#expiration-6

--> The CA certificates are valid for 10 years. The peer, client, and server certificates are valid for three years.

The related code:

https://github.com/openshift/cluster-etcd-operator/blob/main/pkg/tlshelpers/tlshelpers.go#L31-L34

 EtcdCertValidity          = 3 * 365 * 24 * time.Hour
 EtcdCertValidityRefresh   = 2.2 * 365 * 24 * time.Hour
 EtcdCaCertValidity        = 5 * 365 * 24 * time.Hour
 EtcdCaCertValidityRefresh = 4.2 * 365 * 24 * time.Hour