BUG #17866: behavior does not match documentation

The following bug has been logged on the website:

Bug reference:      17866
Logged by:          Евгений Жужнев
Email address:      eugeny@zhuzhnev.com
PostgreSQL version: 15.2
Operating system:   Oracle Linux 9
Description:

sudo -u postgres psql pgc
psql (15.2)
Type "help" for help.

pgc=# SELECT EXTRACT(EPOCH FROM INTERVAL '5 days 3 hours');
    extract    
---------------
 442800.000000
(1 row)
--
But in documentation we can see:
SELECT EXTRACT(EPOCH FROM INTERVAL '5 days 3 hours');
Result: 442800
https://www.postgresql.org/docs/current/functions-datetime.html