REPLACE INTO creates 0 value on autoincrement column

M:1513109 [tmp]>CREATE TABLE `counter_test` (

    ->   `id_counter` bigint(20) unsigned NOT NULL AUTO_INCREMENT,

    ->   `tmstmp` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(),

    ->   `id_ex` bigint(20) NOT NULL,

    ->   `lg` varchar(2) CHARACTER SET ascii COLLATE ascii_bin NOT NULL,

    ->   `title_counter` text CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,

    ->   `content_counter` mediumtext CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,

    ->   PRIMARY KEY (`id_counter`),

    ->   UNIQUE KEY `id_ex_lg_title_counter` (`id_ex`,`lg`,`title_counter`) USING HASH,

    ->   KEY `title_counter` (`title_counter`(255)),

    ->   KEY `id_ex` (`id_ex`)

    -> ) ENGINE=MyISAM AUTO_INCREMENT=18110 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci PACK_KEYS=1 COMMENT='test counter';

Query OK, 0 rows affected (1.303 sec)

M:1513109 [tmp]>SELECT * FROM tmp.`counter_test`  WHERE  id_ex = '197';

Empty set (0.001 sec)

M:1513109 [tmp]>REPLACE INTO tmp.counter_test (id_counter,id_ex, lg, title_counter, content_counter) VALUES (null,'197', 'de', 'logfile', '_get_content_body');

Query OK, 1 row affected (0.000 sec)

M:1513109 [tmp]>SELECT * FROM tmp.`counter_test`  WHERE  id_ex = '197';

+------------+---------------------+-------+----+---------------+-------------------+

| id_counter | tmstmp              | id_ex | lg | title_counter | content_counter   |

+------------+---------------------+-------+----+---------------+-------------------+

|      18110 | 2021-12-27 13:51:23 |   197 | de | logfile       | _get_content_body |

+------------+---------------------+-------+----+---------------+-------------------+

1 row in set (0.000 sec)

M:1513109 [tmp]>REPLACE INTO tmp.counter_test (id_counter,id_ex, lg, title_counter, content_counter) VALUES (null,'197', 'de', 'logfile', '_get_content_body');

Query OK, 2 rows affected (0.000 sec)

M:1513109 [tmp]>SELECT * FROM tmp.`counter_test`  WHERE  id_ex = '197';

+------------+---------------------+-------+----+---------------+-------------------+

| id_counter | tmstmp              | id_ex | lg | title_counter | content_counter   |

+------------+---------------------+-------+----+---------------+-------------------+

|          0 | 2021-12-27 13:51:35 |   197 | de | logfile       | _get_content_body |

+------------+---------------------+-------+----+---------------+-------------------+

1 row in set (0.000 sec)

M:1513109 [tmp]>select version();

+-------------------------------------------+

| version()                                 |

+-------------------------------------------+

| 10.5.10-MariaDB-1:10.5.10+maria~focal-log |

+-------------------------------------------+

1 row in set (0.059 sec)