KubernetesPodOperator  pod_template_file content doesn't support jinja airflow template variables. pod_template_file  is part of templated_fields list. 
https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py#L165

template_fields: Iterable[str] = (        'image',        'cmds',        'arguments',        'env_vars',        'labels',        'config_file',        'pod_template_file',    )

But pod_template_file content is not supporting template variables. pod_template_file can be implemented the way SparkKubernetesOperator implemented using template_ext

https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/spark_kubernetes.py#L46
 template_ext = ('yaml', 'yml', 'json')
airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py
self,
        content: Any,
        context: Dict,
        jinja_env: "jinja2.Environment",
        seen_oids: set,
    ) -> None:
        if id(content) not in seen_oids and isinstance(content, k8s.V1EnvVar):
            seen_oids.add(id(content))
            self._do_render_template_fields(content, ('value', 'name'), context, jinja_env, seen_oids)
            return
        super()._render_nested_template_fields(
            content,
            context,
            jinja_env,
            seen_oids
        )
    @staticmethod
    def create_labels_for_pod(context) -> dict: