BUG #18173: ERROR: could not identify a comparison function for type iso-8859-1

The following bug has been logged on the website:

Bug reference:      18173
Logged by:          JennyJennyChen
Email address:      409800246@qq.com
PostgreSQL version: 16.0
Operating system:   CentOS Linux release 7.9 (Final)
Description:

postgres=# CREATE TABLE test_v(id int,name varchar(30));
CREATE TABLE
postgres=# insert into test_v values(9,'abc'),(9,'def'),(9,'gh'),
(9,'gh');
INSERT 0 4
postgres=# explain (costs off) select distinct
(id,name,'D3Q84xpymM',123,'123') from test_v;
                         QUERY PLAN                          
-------------------------------------------------------------
 Unique
   ->  Sort
         Sort Key: (ROW(id, name, 'D3Q84xpymM', 123, '123'))
         ->  Seq Scan on test_v
(4 rows)

postgres=# select distinct (id,name,'D3Q84xpymM',123,'123') from test_v;
ERROR:  could not identify a comparison function for type unknown
postgres=#