I removed meta from the output in https://github.com/nix-community/nix-eval-jobs/commit/434376f8e1ef653e79b4c2b5a38cba45109152e4 with the intention of adding it back gated by a flag, but that never happened. Adding meta is quite a substantial increase in output size and has some non-trivial performance impact at scale, so it's best to leave it as opt-in.