Why does it redirect back when I try to go to the registration page?

Question

Express.js

There is a registration logic and prescribed routes, when the site is first opened, the registration page opens, the account is registered, recorded in mongo. The main page opens, but when I try to go back to the registration page (/register), it throws me back to the main page, with the same login, I googled it, but I don’t know exactly what to look for.
I'll throw off the register logic and routes, if you need anything else, write. Models for mongo I think do not need to be thrown. Maybe the problem is on the React side?
Routes

//REGISTER
router.post("/register", async (req, res) => {
  try {
    //generate new password
    const salt = await bcrypt.genSalt(10);
    const hashedPassword = await bcrypt.hash(req.body.password, salt);

    //create new user
    const newUser = new User({
      username: req.body.username,
      email: req.body.email,
      password: hashedPassword,
    });

    //save user and respond
    const user = await newUser.save();
    res.status(200).json(user);
  } catch (err) {
    res.status(500).json(err)
  }
});

//LOGIN
router.post("/login", async (req, res) => {
  try {
    const user = await User.findOne({ email: req.body.email });
    !user && res.status(404).json("user not found");

    const validPassword = await bcrypt.compare(req.body.password, user.password)
    !validPassword && res.status(400).json("wrong password")

    res.status(200).json(user)
  } catch (err) {
    res.status(500).json(err)
  }
});

module.exports = router;

main api

const PORT = config.get('PORT') || 5000

mongoose.connect(
  process.env.MONGO_URL,
  { useNewUrlParser: true, useUnifiedTopology: true, useCreateIndex: true },
  () => {
    console.log("Connected to MongoDB");
  }
);
app.use("/images", express.static(path.join(__dirname, "public/images")));

//middleware
app.use(express.json());
app.use(helmet());
app.use(morgan("common"));

const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, "public/images");
  },
  filename: (req, file, cb) => {
    cb(null, req.body.name);
  },
});

const upload = multer({ storage: storage });
app.post("/api/upload", upload.single("file"), (req, res) => {
  try {
    return res.status(200).json("File uploded successfully");
  } catch (error) {
    console.error(error);
  }
});

app.use("/api/auth", authRoute);
app.use("/api/users", userRoute);
app.use("/api/posts", postRoute);
app.use("/api/conversations", conversationRoute);
app.use("/api/messages", messageRoute);

app.listen(PORT, () => {
  console.log("Backend server is running! "+ PORT)
});

Answer 1

So, why are you throwing back? if redirecting to the page does your front, skin the react component of your registration