k8s internal certificates issued by rke2 will be self signed only

the actual rancher + harvester integration might be related to something else and would be nice to get the logs from rancher and agent deployed on the harvester cluster

may be you had a custom cert on rancher and harvester needs the additional CA used to sign the custom rancher cert https://docs.harvesterhci.io/v1.2/advanced/index#additional-ca