A large portion of Flox’s software catalog is based on NixOS nixpkgs. NixOS recently changed the default systems supported to no longer support x86_64-darwin for future LTS versions of nixpkgs after the 26.05 release. For Flox users, the impact is that with the most recent version of Flox 1.14.0 and earlier, the systems attribute has implied support for x86_64-darwin unless at least 1 other system is explicitly listed in manifest.toml. If environments are created with flox init, then still have implied x86_64-darwin support as of Flox 1.14.0.
If you still have x86_64-darwin support (whether implicit or explicit), then many packages like postgresql resolve to the last known nixpkgs revision that contains a build compatible with x86_64-darwin, which is currently an older release of postgresql. If you do not need support for x86_64-darwin, then we strongly recommend making your list of systems supported explicit rather than implicit in manifest.toml like in this example:
[options]
systems = ["aarch64-darwin", "aarch64-linux", "x86_64-linux"]
See this gist as an example of the impact of removing x86_64-darwin and then having the catalog resolve to a newer version of software.
The Flox team is considering how to proceed with x86_64-darwin support and will provide an update once we have a path forward.