Wrong result ('pNuLl_' instead of NULL) in the TEXT column when LEFT OUTER JOIN is used with WHERE condition

MariaDB [test]> create table A (id bigint, vc varchar(100), t text, fk_b bigint) engine = Columnstore;

Query OK, 0 rows affected (10.585 sec)

MariaDB [test]> create table B (id bigint, vc varchar(100)) engine = Columnstore;

Query OK, 0 rows affected (9.859 sec)

MariaDB [test]> insert into A values(11, 'abc', 'XYZ', 2);

Query OK, 1 row affected (2.188 sec)

MariaDB [test]> insert into B values (1, 'bla'), (2, 'doh');

Query OK, 2 rows affected (1.672 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [test]> select A.t from B left outer join A on A.fk_b = B.id;

+------+

| t    |

+------+

| NULL |

| XYZ  |

+------+

2 rows in set (0.321 sec)

MariaDB [test]> select left(A.vc,20) from B left outer join A on A.fk_b = B.id where B.id = 1;

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

| left(A.vc,20) |

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

| NULL          |

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

1 row in set (0.370 sec)

MariaDB [test]> select left(A.t,20) from B left outer join A on A.fk_b = B.id where B.id = 1;

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

| left(A.t,20)         |

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

| pNuLl_               |

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

1 row in set (0.037 sec)

MariaDB [test]> alter table A engine = InnoDB;

Query OK, 1 row affected (6.289 sec)               

Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]> alter table B engine = InnoDB;

Query OK, 2 rows affected (6.121 sec)              

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [test]> select left(A.t,20) from B left outer join A on A.fk_b = B.id where B.id = 1;

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

| left(A.t,20) |

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

| NULL         |

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

1 row in set (0.104 sec)