pg_getnameinfo_all() failed: Temporary failure in name resolution

[Ron Johnson <ronljohnsonjr@xxxxxxxxx>]

PG 9.6.24 (Yes, I know it's EOL.)

I'm seeing lots of these in the postgresql log file:

2023-11-24 15:09:02.224 EST             [unknown]       [unknown]       18163           [unknown]       01000   WARNING:  01000: pg_getnameinfo_all() failed: Temporary failure in name resolution
2023-11-24 15:09:02.224 EST             [unknown]       [unknown]       18163           [unknown]       01000   LOCATION:  BackendInitialize, postmaster.c:4220

What name is postgresql failing to resolve?