When installing through Helm and using a custom releaseName, the service is created with a name “cert-manager<releaseName>-webhook”, and the MutatingWebhookConfiguration and ValidatingWebhookConfiguration are also created for this name.
In these objects there is a configuration that points the name of the Webhook and the Pod/Cert-Manager points precisely to the Service that has the name that is in these objects.
When removing the HelmRelease to install a new one with a different name, these MutatingWebhookConfiguration and ValidatingWebhookConfiguration objects are not deleted, thus becoming garbage in the environment and conflicting with the new objects.
The Pod/Cert-Manager continues to see the old objects and use their settings to try to make the Webhook call.
In short, I solved it by removing the objects. And installing Cert-Manager again:
kubectl get validatingwebhookconfiguration.admissionregistration.k8s.io
kubectl delete validatingwebhookconfiguration.admissionregistration.k8s.io/<Junk Object>
kubectl get mutatingwebhookconfiguration.admissionregistration.k8s.io
kubectl delete mutatingwebhookconfiguration.admissionregistration.k8s.io/<Junk Object>