LIKE function has error behavior on the fields in which the collation is xxx_unicode_xx

MariaDB [(none)]> use test;

Database changed

MariaDB [test]> create table like_test(name varchar(20) character set 'utf8' collate 'utf8_unicode_ci');

Query OK, 0 rows affected (0.012 sec)

MariaDB [test]> insert into like_test values('radio! test');

Query OK, 1 row affected (0.003 sec)

MariaDB [test]> select * from like_test where name like '%!!%' escape '!';

Empty set (0.002 sec) -- this is wrong!

MariaDB [test]> ALTER TABLE like_test CHANGE COLUMN name name VARCHAR(20) CHARACTER SET 'utf8' COLLATE 'utf8_general_ci';

Query OK, 1 row affected (0.032 sec)

Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]> select * from like_test where name like '%!!%' escape '!';

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

| name        |

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

| radio! test |

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

1 row in set (0.001 sec)