CREATE OR REPLACE FUNCTION public.autonomous (p_script text)
RETURNS SETOF record
LANGUAGE plpgsql
VOLATILE STRICT PARALLEL UNSAFE
AS $autonomous$
DECLARE
l_id integer;
BEGIN
l_id := pg_background_launch(p_script);
RETURN QUERY SELECT * FROM pg_background_result(l_id) AS (r record);
END;
$autonomous$;
 
SELECT * FROM autonomous('SELECT now()') AS (a timestamptz);
 
SQL Error [42804]: ERROR: structure of query does not match function result type
  Detail: Returned type record does not match expected type timestamp with time zone in column 1.
  Where: SQL statement "SELECT * FROM pg_background_result(l_id) AS (r record)"
PL/pgSQL function autonomous(text) line 6 at RETURN QUERY