The hyprland cachix isn’t doing you any good if you’re not using their flake. So you can remove that.
I also don’t see any overlay, but you also commented out all your packages, so hard to tell what would obviously get rebuilt.
Again, though, if the concern is librewolf then it will be cached soon, see Librewolf Marked as Insecure - #3 by mBornand. (Insecure packages are not cached by hydra, as a policy.)