Maybe add it to the correct setting location

nixos/server/package-configs/forgejo/default.nix

@@ -71,15 +71,15 @@
         IS_INPUT_FILE = true
         RENDER_CONTENT_MODE = no-sanitizer
       ";
-    };
-    markup.sanitizer.juypter0 = "
-      ; Jupyter chiefly uses divs
-      ELEMENT = div
-      ; we will need access to html classes later
-      ALLOW_ATTR = class
-      ; we don't mind which classes we keep, so let's keep all of them
-      REGEXP =
+      markup.sanitizer.juypter0 = "
+        ; Jupyter chiefly uses divs
+        ELEMENT = div
+        ; we will need access to html classes later
+        ALLOW_ATTR = class
+        ; we don't mind which classes we keep, so let's keep all of them
+        REGEXP =
     ";
+    };
   };
 
   services.nginx = {