Query parameters are lost during locale redirection

[tsurumeso]

Description

I am deploying a Next.js (Pages Router) application with i18n enabled using OpenNext.

When a user accesses the root path (/) and is redirected to a non-default locale (e.g., /en) based on their browser's language settings, any query parameters present in the original URL are lost during the redirection.

This behavior differs from the local Next.js environment (next dev / next start), where query parameters are correctly preserved.

Environment

OpenNext version: 3.9.4
Next.js version: 14.2.33

To Reproduce

1. Initialize a Next.js project

   npx create-next-app@14 . 
   # Select "Pages Router"
   npm install next-i18next react-i18next i18next

2. Configure i18n

   // next-i18next.config.mjs
   export const i18n = {
       defaultLocale: 'ja',
       locales: ['en', 'ja'],
   }

   // next.config.mjs
   import { i18n } from './next-i18next.config.mjs';
   
   const nextConfig = {
       i18n,
       reactStrictMode: true,
   };
   
   export default nextConfig;

3. Deploy using SST

   npx sst@latest init
   npx sst deploy --stage production

4. Change your browser's preferred language to English.

5. Access the deployed root URL with query parameters: https://example.com/?xxx=yyy

Expected behavior

The user should be redirected to the English locale path with query parameters preserved: https://example.com/en?xxx=yyy

Actual behavior

The user is redirected to the English locale path, but query parameters are missing: https://example.com/en