Case when~ vs case ~ when ~

mysql>create table t2(id int, nm varchar(10)) engine=columnstore;

mysql>insert into t2 values( 1, 'AAA');
mysql>insert into t2 values( 2, 'BBB');
mysql>insert into t2 values( 3, 'CCC');
mysql>

select
id,nm,
charset(nm),
collation(nm),
charset('AAA'),
collation('AAA'),
(case when nm='AAA' then 1 else 0 end) as nmchk1,
(case nm when 'AAA' then 1 else 0 end) as nmchk2
from t2;
------------------------------------------------------------------------------+

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

------------------------------------------------------------------------------+
3 rows in set (0.01 sec)

------>>>> The values of case when and chse ~ when are returned differently. It looks like a bug. Please confirm.