JSON_ARRAY returns list of String when given a list of integer by passing in variables in stored procedure

DELIMITER //

DROP PROCEDURE IF EXISTS test;

CREATE PROCEDURE test(OUT testOutput TEXT)

BEGIN

  DECLARE C1 INT;

  DECLARE C2 INT;

  select count(*) from `tb1` into C1;

  select count(*) from `tb2` into C2;

  select JSON_ARRAY(C1

           , C2) INTO testOutput;

END;

//

DELIMITER ;

CALL test(@testOutput);

SELECT @testOutput;

select JSON_ARRAY((select count(*) from `tb1`)

           , C2) INTO testOutput;