Jacascript -> Browser won't set cookie react / express

Question

I'm trying to use JWT and cookies to handle authentication in an express / react app. They are running on two different domains. In development, I just set a proxy inside my package.json file in the frontend, and everything worked. Now I can't get it to work in the production. I've gone through several posts on here already, and I'm following the steps given, but can't figure out what I'm doing wrong / different.

Unable to set cookie on a different domain. Express and React

Express cors not allowing credentials

In app.js inside my backend I have the following cors settings:

app.use(
  cors({
    origin: 'https://social-app-frontend.netlify.app',
    credentials: true,
    exposedHeaders: ['set-cookie'],
  })
);

And the following middleware:

app.use((req, res, next) => {
  res.header(
    'Access-Control-Allow-Origin',
    'https://social-app-frontend.netlify.app'
  );
  res.header('Access-Control-Allow-Credentials', true);
  res.header(
    'Access-Control-Allow-Methods',
    'GET,PUT,POST,DELETE,UPDATE,OPTIONS'
  );
  res.header(
    'Access-Control-Allow-Headers',
    'X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept'
  );
  next();
});

And this how I'm sending the cookie:

const createAndSendToken = (user, statusCode, req, res) => {
  const token = signToken(user._id);
  const ninetyDays = 90 * 24 * 60 * 60 * 1000;
  res.cookie('jwt', token, {
    expires: new Date(Date.now() + ninetyDays),
    httpOnly: true,
    secure: true,
    domain: 'social-app-frontend.netlify.app',
    sameSite: 'None',
  });

  // remove password from output
  user.password = null;

  res.status(statusCode).json({
    status: 'success',
    token,
    data: { user },
  });
};

On the frontend this is my axios instance:

const instance = axios.create({
  baseURL: 'https://social-backend-123.herokuapp.com/users',
  timeout: 20000,
  withCredentials: true,
});

The request gets made a as a post request. In my network tab, I can see the login request, and I can see the Set-cookie header on the response with a valid jwt token. But I get this warning in my console : Cookie “jwt” has been rejected for invalid domain.

Can anyone point me in the right direction please? Thanks!