Why a postgreSQL timestamp with time zone at a certain time zone is printed without the time zone

Question

When I ask PostgreSQL for a timestamp with time zone at a certain time zone, it does not print the time zone:

SELECT now()::timestamp WITH TIME ZONE AT TIME ZONE 'CST';

          timezone          
----------------------------
 2023-11-08 06:00:28.983353
(1 row)

Whereas:

SELECT now()::timestamp WITH TIME ZONE;

              now              
-------------------------------
 2023-11-08 12:01:00.704341+00
(1 row)

Does print the time zone (+00)?

Why?

I was naturally expecting a time zone indication with the first query. Or, when asked without:

SELECT now()::timestamp WITHOUT TIME ZONE AT TIME ZONE 'CST';

           timezone            
-------------------------------
 2023-11-08 18:08:25.911371+00
(1 row)

it does print it.