this might just be it

overlays/nixpak/firefox.nix

@@ -3,10 +3,10 @@
 # https://github.com/schizofox/schizofox/blob/cdf69b2a445ff12680657a3bd44ce7c406bf2ae6/flake/modules/home-manager/default.nix
 
 { lib, ... }: final: prev: {
-  firefox-esr-wrapped = let
+  firefox-esr-sandboxed= let
     sandboxed-firefox-esr = prev.mkNixPak {
       config = { sloth, ... }: {
-        app.package = prev.firefox-esr;
+        app.package = prev.firefox-esr-unwrapped;
         app.binPath = "bin/firefox-esr-wrapped";
         flatpak.appId = "org.mozilla.firefox";
 
@@ -58,7 +58,7 @@
             "/sys/bus/pci"
             "/etc/resolv.conf"
             "/etc/localtime"
-            ["${prev.firefox-esr}/lib/firefox" "/app/etc/firefox"]
+            ["${prev.firefox-esr-unwrapped}/lib/firefox" "/app/etc/firefox"]
             (sloth.concat' sloth.xdgConfigHome "/dconf")
             (sloth.concat' sloth.xdgConfigHome "/gtk-2.0")
             (sloth.concat' sloth.xdgConfigHome "/gtk-3.0")
@@ -75,23 +75,5 @@
       };
     };
   in
-    prev.wrapFirefox (sandboxed-firefox-esr.config.env // {
-      inherit (prev.firefox-esr)
-        version
-        meta
-        langPath
-        updateScript
-        pkgconfig
-        buildPackages
-        patches
-        extraPatches
-        extraPrefs
-        extraPolicies
-        nativeMessagingHosts
-        cfg;
-      gtk3 = prev.gtk3;
-    }) {
-      applicationName = "firefox-esr-wrapped";
-      desktopName = "Firefox ESR (Sandboxed)";
-    };
+    prev.wrapFirefox sandboxed-firefox-esr.config.env;
 }