Column cannot be null if trigger exists

if the before insert trigger exists this script give an error "Column 'k' cannot be null", but Column k not null.

I tested lot of mariadb version and config, there were some servers got good results.
When I tested a fresh ubuntu 24.04 with 11.11-MariaDB-ubu2404 got error (this from mariadb repo).
When I tested with ubuntu with own mariadb repo (10.11.11-MariaDB), was good result.
Maybe it was good in 10.11.10.

DROP TABLE if exists tmp;

CREATE TABLE tmp (

  `k` bigint(20) unsigned NOT NULL,

  `rowid` bigint(20) unsigned NOT NULL AUTO_INCREMENT,

  PRIMARY KEY (rowid)

) ENGINE=innodb ;

DELIMITER //

CREATE  TRIGGER `tmp_before_insert` BEFORE INSERT ON `tmp` FOR EACH ROW BEGIN

END;

//

DELIMITER ;

TRUNCATE tmp;

INSERT INTO tmp (k)

SELECT 1

UNION

SELECT 2

UNION

SELECT 3;

SELECT * FROM tmp;

DROP TABLE if exists tmp;