Unit xdg-desktop-portal.service could not be found

Help
1

I’m currently running into a strange problem on my nixos system: waybar suddenly stopped working. I’m using flake-based nixos+home-manager+sway.

I have two machines, centaur and nova. nova is working fine, on centaur, waybar suddenly stopped working. I did not change my settings or rebuild the system (as far as I can remember). Going back to previous generations also does not restore waybar functuality.

The config is very similar between both systems, the main difference is nova uses nvidia while centaur uses AMD.

I think the error is due to xdg-desktop-portal.service not being available. In particular, on machine centaur, I get this message

$ systemctl --user status xdg-desktop-portal
Unit xdg-desktop-portal.service could not be found.

while on nova the service is running.

I tried different combinations of

# configuration.nix
  xdg.portal = {
    enable = true;
    extraPortals = [
      pkgs.xdg-desktop-portal-wlr
      pkgs.xdg-desktop-portal-gtk
    ];

    wlr = {
      enable = true;
    };
  };
  environment.pathsToLink = [
    "/share/xdg-desktop-portal"
    "/share/applications"
  ];

and

# home.nix
  xdg.portal = {
    enable = true;
    config.common.default = "*";
    extraPortals = [ pkgs.xdg-desktop-portal-gtk ];
  };

but nothing seems to work.

Can anyone give me a pointer what to look for?