empty result with "case .. when" with where condition and multiple parameter in "IN" clause

create database ct;

use ct;

create table test_inno (astr VARCHAR(50))ENGINE = INNODB ;

create table test_mcs (astr VARCHAR(50))ENGINE = COLUMNSTORE ;

INSERT INTO test_inno (astr) value('test');

INSERT INTO test_mcs (astr) value('test');

MariaDB [t]> SELECT astr FROM test_inno WHERE  CASE WHEN COALESCE('0') = '0' THEN  astr IN ('test') END;

+------+

| astr |

+------+

| test |

+------+

1 row in set (0.00 sec)

MariaDB [t]> SELECT astr FROM test_mcs WHERE  CASE WHEN COALESCE('0') = '0' THEN  astr IN ('test') END;

+------+

| astr |

+------+

| test |

+------+

1 row in set, 1 warning (0.03 sec)

MariaDB [t]> SELECT astr FROM test_inno WHERE  CASE WHEN COALESCE('0') = '0' THEN  astr IN ('test','unknown') END;

+------+

| astr |

+------+

| test |

+------+

1 row in set (0.00 sec)

MariaDB [t]> SELECT astr FROM test_mcs WHERE  CASE WHEN COALESCE('0') = '0' THEN  astr IN ('test','unknown') END;

Empty set, 1 warning (0.01 sec)