I have just added nix-colors to my flake, and am attempting to use it in home-manager.
I was getting errors at first because all the color values I tried were 12-character hex strings, instead of 6. Upon inspection the 12-character strings were the 6-character strings repeated twice. For example, instead of 282828 for nix-colors.colorSchemes.gruvbox-mark-medium.base00, I am getting 282828282828.

The error seems to be consistent, so I'm using builtins.subString 0 6 as a temporary workaround.

The relevant portion from my flake.lock is as follows

    "nix-colors": {
      "inputs": {
        "base16-schemes": "base16-schemes",
        "nixpkgs-lib": "nixpkgs-lib"
      },
      "locked": {
        "lastModified": 1707825078,
        "narHash": "sha256-hTfge2J2W+42SZ7VHXkf4kjU+qzFqPeC9k66jAUBMHk=",
        "owner": "misterio77",
        "repo": "nix-colors",
        "rev": "b01f024090d2c4fc3152cd0cf12027a7b8453ba1",
        "type": "github"
      },
      "original": {
        "owner": "misterio77",
        "repo": "nix-colors",
        "type": "github"
      }
    },