[FAIL]** Found profiles outside of /nix/var/nix/profiles

Why did the installer create a symlink…
.nix-profile -> /home/cmyk/.local/state/nix/profiles/profile

… if it’s going to complain when you run a nix config test?
How is this properly set up? I could find nothing conclusive in docs.
Also, why does the installer not set $NIX_CONF_DIR?

cmyk@ubuntu: ~ $ nix config check
[PASS] PATH contains only one nix version.
[FAIL] Found profiles outside of /nix/var/nix/profiles.
The generation this profile points to might not have a gcroot and could be
garbage collected, resulting in broken symlinks.

   "/home/cmyk/.nix-profile/bin"

[PASS] Client protocol matches store protocol.
[INFO] You are trusted by store uri: daemon