I can not set a token FIrebase

Question

app.post('/authenticate', async function(req, res){
    const secret="secret"
    const { username, password } = req.body;
    var passwordToCheck = await getData("users","admin");
    passwordToCheck=passwordToCheck.password;
    checkPassword(password, passwordToCheck, function (err,same) {  
        if(err){
          console.log("Internal error")
            res.status(500)
              .json({
              error: 'Internal error please try again'
            });
        }else if(!same){
          console.log("Wrong Email")
            res.status(401)
              .json({
              error: 'Incorrect email or password'
            });
        }else{
          const payload = { username };
          const expiresIn = 60 * 60 * 24 * 5 * 1000;
          const options = { maxAge: expiresIn, httpOnly: true, secure: true, path: "/"};
          const token = jwt.sign(payload, secret, {
            expiresIn: '1h'

          });
          res.setHeader('Cache-Control', 'private');
          res.cookie('__session', token, options).sendStatus(200);
      }
    });
  });

So this code works when running locally but not when I deploy it. The cookie will not be set and I cant figure out why. My backend is hosted using firebase functions and my frontend is hosted with firebase hosting. Thanks.