autoconfig is ignored

[DADA30000]

• I've updated the flake input to the latest version
• I've correctly set up my XDG portals

Describe the bug

It seems that autoconfig is ignored by zen, when using zen from this flake, even though all files are indeed in a wrapper dir, located in right places, like
/nix/store/3ryz5jliq73497wzbp932zcq5pbks7hc-zen-twilight-1.18t/lib/zen-bin-1.18t/defaults/pref/autoconfig.js
/nix/store/3ryz5jliq73497wzbp932zcq5pbks7hc-zen-twilight-1.18t/lib/zen-bin-1.18t/mozilla.cfg

To Reproduce

Start Zen and see if prefs starting with general.config changed, obscure value should change to 0, and there should be a pref created called general.config.filename

System Information

• OS: NixOS Unstable 26.05.20251130.2d293cb (Yarara)
• Zen Browser version: twilight
• Desktop environment / Compositor / WM: Hyprland

Additional context

This doesn't happen if I run zen from official tarball using steam-run

[DADA30000]

left - from tarball, right - from this flake

[DADA30000]

even hashes of autoconfig.js are the same, so something is wrong with the way this flake makes zen run