Why is my fetch() sending an empty JSON body?

I've been trying to send a JSON data using fetch but the backend receives an empty object.In my Client JS I have

const user = "company1";const username = "muneeb";const data = {user, username};fetch("http://127.0.0.1:3000/users/api/login", {    method: 'POST',    body: JSON.stringify(data)}).then((response) => {    console.log(response);});

The server side has:

router.post('/users/api/login', async (req, res, next) => {    try {        // console.log(request.body);        const request = JSON.stringify(req.body);        let imageTitles = [];        console.log(request);        *its random from here on out but you get the idea*        await components.getImages(imageTitles);        const finalKey = imageTitles.join("");        let images = await components.output(req.body.user ,req.body.username);        res.send(components.jsonConverter(imageTitles, images)); //---Top priority        db.setPassword(req.body.user, req.body.username , finalKey);    } catch (err) {        console.log(err);        res.send(err).sendStatus(500);    };})

A few things I have already tried :

It works perfectly in Insomnia(postman).

express.json() is present , it helped me go from undefined to blank JSON.

I have enabled cors settings.

That's it for now.