Earlier quoted context omitted.
Lix is a (nixpkgs-compatible) fork of Nix, led by Nix community members that don't get along with the core Nix team. At this point, the primary reason to switch to Lix would be if you trusted the Lix folks more than the core Nix team
Didn't get along is an understatement. They gaslit and destroyed the little bit of leadership structure of NixOS had through harassment and bullying.
It's very bad and one can simply look through the Discourse and GitHub issues from earlier this year to discover the full extent of the problem. Watch how they turn a security issue into PR now, this is just a microcosm of the dishonesty.