And yet pg_basebackup doesn't complain about an invalid option. (Technically, this is a bug; I first noticed it a week after copying a script from a PG 15 server to five PG 14 servers, and running it quite a few times without fail.)
Seems a bit suspect, but as your script doesn’t mention tar the option itself is apparently ignored, I guess silently.
Does this mean that "--compress=server-zst" is only relevant with --format=tar?
Assuming this isn’t an actual regression in behavior in a patch-released older version
My apologies for not mentioning the version: 14.12-1PGDG-rhel8.
I don’t see us adding an error message at this point.