Cannot get correct static files after refreshing except index page

Question

When I refresh page on index route (/) and login page (/login), it works fine.

However, my website gets error as I refresh on other routes, for example /user/123456.

Because no matter what the request is, the browser always gets HTML file.
Thus, both of the content in main.css and main.js are HTML, and the browser error.

I have already read the README of create-react-app.
Whether I use serve package ($serve -s build -p 80) or express, it will produce the strange bug.

Following is my server code:

//server.js
const express = require('express');
const path = require('path');
app.use(express.static(path.join(__dirname, 'build')));
app.get('/*', (req, res) => {
  res.sendFile(path.join(__dirname, 'build', 'index.html'));
});
const PORT = process.env.PORT || 80;
app.listen(PORT, () => {
  console.log(`Production Express server running at localhost:${PORT}`);
});

Edit: I have figured out where caused the problem.
I created a new project, and compared it to mine. The path of static files in the new project is absolute, but in my project is relative.
As a result, I delete "homepage": "." in the package.json.

//package.json
{ ....
  dependencies:{....},
  ....,
- "homepage": "."
}

Everything works as expected now. How am I careless...

Answer 1

I have figured out where caused the problem. I created a new project, and compared it to mine. The path of static files in the new project is absolute, but in my project is relative. As a result, I delete "homepage": "." in the package.json.

//package.json
{ ....
 dependencies:{....},
 ....,
- "homepage": "."
}

Everything works as expected now. How am I careless...