I was trying to install eza v0.23.3 from a flake (using the commit associated with that version). I passed in a latest nixpkgs commit (NixOS/nixpkgs@5263bc6 for example) and the package failed to build. Because the flake uses nixpkgs-unstable, the failure also occurred when not passing in my own nixpkgs version. I got the following error when trying to build eza:

error: darwin.apple_sdk_11_0 has been removed as it was a legacy compatibility stub; see <https://nixos.org/manual/nixpkgs/stable/#sec-darwin-legacy-frameworks> for migration instructions

I was able to fix this by overriding the nixpkgs input to an older version (using NixOS/nixpkgs@31cab29 worked for example).