I confirm that upgrading next (from 12.2.2, not working) to 12.2.5 fixes this issue.

[luke-hanwook]

    I confirm that upgrading next (from 12.2.2, not working) to 12.2.5 fixes this issue.

I was using Twitter provider.
Here's my code if anyone's interested or struggling 🧐:

./src/middleware.js :

import { withAuth } from 'next-auth/middleware';

export default withAuth(
  // `withAuth` augments your `Request` with the user's token.
  function middleware(req) {
    console.log(req.nextauth.token); // This was null in 12.2.2, and working in 12.2.5
  },
  {
    callbacks: {
      authorized: ({ token }) => {
        // This is to only allow access to these Twitter user ids.
        return ['44196397', '15540222'].includes(token?.sub); // Elon Musk & Guillermo Rauch (NextJS creator), welcome :)
      },
    },
  }
);

export const config = { matcher: ['/movies/:path*'] };

./src/pages/api/[...nextauth].ts

/* eslint-disable no-param-reassign */
import type { NextAuthOptions } from 'next-auth';
import NextAuth from 'next-auth';
import TwitterProvider from 'next-auth/providers/twitter';

export const authOptions: NextAuthOptions = {
  providers: [
    TwitterProvider({
      clientId: process.env.TWITTER_CONSUMER_KEY!,
      clientSecret: process.env.TWITTER_CONSUMER_SECRET!,
    }),
  ],
  pages: {
    signIn: '/auth/signin',
  },
  session: {
    strategy: 'jwt',
    maxAge: 90 * 24 * 60 * 60, // 90 days, change it as you like
  },
  callbacks: {
    async jwt({ token, user }) {
      if (user) {
        token.sub = user.id;
      }
      return token;
    },
    async session({ session, token }) {
      if (token) {
        session.user = token;
      }
      return session;
    },
  },
};

export default NextAuth(authOptions);

Originally posted by @kodsu in nextauthjs/next-auth#5008 (comment)