NodeJS sending index.js file as response – Plesk

So i built an app using NodeJS in the backend and ReactJs in the frontend and everything worked well while testing. Now everytime i make a request in the production server, the request sends the index.html content instead of the data.

Here is the content of server.js

//Some imports

app.use(
  bodyParser.urlencoded({
    extended: true,
    limit: "100mb",
    parameterLimit: 1000000,
  })
);
const port = 5000;

app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(cors());

app.use(express.static(path.join(__dirname, 'build')));

app.set("trust proxy", true);

...

app.post('/api/test', async (req, res) => {
  res.send("Hello world!")
});

//Sample of the nodejs response

//Sample of a function that makes a request

//This belongs to the call function that checks for the validity of the token!

        //Main Request
        await api.post(EndPoint, BodyObject, { headers: headers })
            .then(async function (response) {

                //A resposta da main pode ser 2 coisas
                //--A resposta do request com a data
                //--A resposta do /api/auth com a mensagem a dizer que o token está invalido  

                //Unsuccessful request
                if (response.data == "Access Token expired" || response.data == "There's something wrong with token") {
                    //Store invalid to call /newToken endPoint
                    tokenValidity = false;
                    //Unsuccessful request
                } else if (response.data == "Invalid Signature") {
                    //Redirect to Login
                    window.location.href = "https://www.link.pt/login";
                }
                //Successful request
                else {
                    serverResponse = response.data;
                }
            })

//Sample of an endpoint in server.js