Thank you very much, you did my day!

Based on logs I did not grasp, that headers key should be omitted, nor ChatGPT did provide any help - except of suggestion to store the key in the password field of Connection UI and mention headers in a DAG like this

    server_info = HttpOperator(
        task_id="info",
        http_conn_id="api",
        endpoint="/serverInfo",
        method="GET",
        headers={
            "Authorization": "Bearer {{ conn.jira_api.password }}",
            "Content-Type": "application/json"
        },
        log_response=True,
        do_xcom_push=False, 
    )