pgpass file in postresql.auto.conf?

Hey folks,

In the interest of automation, I've set up a pgpass file for my 
pg_basebackup between master and standby.  This all works, thusly:

pg_basebackup -d 
'postgres://repuser@10.1.1.1:5432/foo?sslmode=verify-ca' -F p 
--wal-method=stream -P -R -D /var/db/postgres/data17-test3

However, instead of the password getting baked into the pgsql.auto.conf, 
the reference to the passfile gets put in, instead:

# Do not edit this file manually!
# It will be overwritten by the ALTER SYSTEM command.
primary_conninfo = 'user=repuser passfile=''/var/db/postgres/.pgpass'' 
channel_binding=prefer host=10.1.1.1 port=5432 sslmode=''verify-ca'' 
sslnegotiation=postgres sslcompression=0 sslcertmode=allow sslsni=1 
ssl_min_protocol_version=TLSv1.2 gssencmode=disable krbsrvname=postgres 
gssdelegation=0 target_session_attrs=any load_balance_hosts=disable 
dbname=foo'

But it seems postgres won't actually read the passfile.

Sep 26 12:01:27 hostname postgres[42455]: [7-1] 2025-09-26 12:01:27.658 
UTC [42455] FATAL:  could not connect to the primary server: connection to 
server at "10.1.1.1", port 5432 failed: fe_sendauth: no password supplied

Am I doing something wrong here?

I'm loathe to hand-edit the file, because of that warning there.

Why does pg_basebackup put a reference to a file it it won't read it?

Is there an alter system command that can be used to properly populate the 
password into this file?

-Dan