fix

config-paths-needed.json

@@ -1,5 +1,6 @@
 [
   [ "selfprivacy", "domain" ],
+  [ "selfprivacy", "username" ],
   [ "selfprivacy", "modules", "auth", "enable" ],
   [ "selfprivacy", "modules", "mastodon" ],
   [ "selfprivacy", "passthru", "auth" ],

module.nix

@@ -167,7 +167,7 @@ in
           POSTGRES_USER = db.user;
           POSTGRES_HOST = db.host;
           USERDATA_FILE_PATH = "/var/lib/mastodon/.userdata.json";
-          OWNER_USERNAME = db.username;
+          OWNER_USERNAME = sp.username;
         };
         serviceConfig = {
           Slice = "mastodon.slice";