Placeholder dont seem to work with nix-darwin

[Alt-iOS]

Hi, this config

let
  packageSet = import ./packages.nix { inherit pkgs; };
  opencode-package = pkgs.callPackage ../custom/opencode { };
in
{

  sops.defaultSopsFile = ../secrets/secrets.yaml;
  sops.age.keyFile = "/Users/victor/.config/sops/age/keys.txt";
  # needed to stop warnings about sshkeys missing, the above path is the corerct source
  sops.gnupg.sshKeyPaths = [ ];
  sops.age.sshKeyPaths = [ ];
  sops.secrets.github_token = {
    owner = "victor";
  };
  sops.secrets.tavily_api_key = {
    owner = "victor";
  };

  environment.systemPackages = [
    pkgs.lazygit
    pkgs.neovim
    pkgs.nushell
    pkgs.nufmt
    pkgs.tmux
    pkgs.nixfmt-rfc-style
    pkgs.jujutsu
    pkgs.git
    pkgs.direnv
    opencode-package
  ] ++ packageSet.allPackages;

  nix.settings = {
    experimental-features = "nix-command flakes";
    extra-platforms = "x86_64-darwin aarch64-darwin";
    extra-access-tokens = [
      "github.com=${config.sops.placeholder.github_token}"
    ];
  };

  programs.fish.enable = true;
  users.users."victor".shell = pkgs.fish;
  users.knownUsers = [ "victor" ];
  users.users.victor.uid = 501;
  system.configurationRevision = config.selfRev or config.selfDirtyRev or null;
  system.stateVersion = 6;
  system.primaryUser = "victor";
  nixpkgs.hostPlatform = "aarch64-darwin";
  environment.etc."nix-darwin".source = "/Users/victor/.config/nix-darwin";
  environment.variables.TAVILY_API_KEY = config.sops.placeholder.tavily_api_key;
  programs.direnv.enable = true;
}

gives me this error, is this not the appropiate way to use place holders?

error: attribute 'tavily_api_key' missing
       at /nix/store/jdsi3bp9hzgxzhkgrfvspp2hihab4azn-source/nix-darwin/modules/configuration.nix:50:42:
           49|   environment.etc."nix-darwin".source = "/Users/victor/.config/nix-darwin";
           50|   environment.variables.TAVILY_API_KEY = config.sops.placeholder.tavily_api_key;
             |                                          ^
           51|   programs.direnv.enable = true;

and also this error

    error: attribute 'github_token' missing
       at /nix/store/wqnvh666b4dxjp36qfdhidl4yvajvbbb-source/nix-darwin/modules/configuration.nix:37:21:
           36|     extra-access-tokens = [
           37|       "github.com=${config.sops.placeholder.github_token}"
             |                     ^
           38|     ];