I think people are generally confused the different meanings of reproducibility in this case. The reproducibility that Nix initially aimed at is: multiple evalu

I think people are generally confused the different meanings of reproducibility in this case. The reproducibility that Nix initially aimed at is: multiple evaluations of the same derivations will lead to the same normalized store .drv. For a long time they were not completely reproducible, because evaluation could depend on environment variables, etc. But flakes have (completely ?) closed this hole. So, the reproducibility in Nix means that evaluating the same package set will lead to the same set of build recipes (.drvs). However, this doesn't say much about build artifact reproducibility. A package set could always evaluate to the same drvs, but if all the source packages choose what to build based on random() > 0.5, then there is no of build artifacts at all. This type of reproducibility is spearheaded by Debian and Arch more than Nix.