Confused with PostgreSQL on Synology NAS

Greetings hackers:

I have a Synology NAS, and there is a PostgreSQL version 11.11 on it. I tried to modify pg_hba.conf file and add a new rule for external access.

But there is a strange thing, the $PGDATA is /var/services/pgsql, so changing the file on $PGDATA/pg_hba.conf maybe ok, but not. See below:

Then I tried to find the pg_hba.conf file, there is another one on /etc/postgresql/pg_hba.conf, this is actually the right file.

My question is that PostgreSQL usually use $PGDATA/pg_hba.conf as the access control file, is there other way to specify conf file in other place?

Best regards,
Chris