Passport Session resets after redirect?

Question

I'm trying to create a react app with socketio and oauth(passport-spotify) in the backend, but I can't access user information in socketIO after successful authorization and redirection.

I put the barebone project on github here https://github.com/Agonyagonyagony/PassportSocketIOAuth

passport.use(
  new SpotifyStrategy(
    {
      clientID: process.env.SPOTIFY_CLIENT_ID,
      clientSecret: process.env.SPOTIFY_CLIENT_SECRET,
      callbackURL: "http://localhost:3000/auth/spotify/callback",
      passReqToCallback: true,
    },
    function (req, accessToken, refreshToken, expires_in, profile, done) {
      const user = profile;
      done(null, user);
    }
  )
);
[...]
app.get(
  "/auth/spotify/callback",
  passport.authenticate("spotify", { failureRedirect: "/login" }),
  function (req, res) {
    console.log(req.session);
    // console.log(req.session.cookie);
    // Successful authentication, redirect home.
    // // res.cookie("connect.sid", JSON.stringify(req.session.cookie));
    res.redirect("/");
  }
);
[...]
io.on("connection", (socket: Socket) => {
  console.log("socket initialization completed");
  console.log(socket.request.user ?? "none");
  console.log(socket.request.passport ?? "none");
  socket.on("say", (data) => {
    console.log(data, "received information");
    socket.emit("message", { hello: "who are you" });
  });
});

The callback function gets the profile information, but the redirect to my frontend seems to reset the session? I tried serving a simple html with socketio within express and that worked, but that's not really an option for development.

I also tried writing cookies with the redirect. That showed a cookie, but the io connection didn't seem to care.