A minimal example with two files:

index.Rmd:

---
title: "测试"
---

# 前言

这里要介绍这本书主要要讲什么。

01.Rmd:

# 测试章节

本来这里要将重要内容的。

And one output configuration yaml file:

bookdown::gitbook:
  lib_dir: "book_assets"
  split_by: section
  md_extensions: -ascii_identifiers

After build the book on Windows OS, the navigation-next reference link in index.html is as follow:

<a href="娴嬭瘯绔犺妭.html" class="navigation navigation-next navigation-unique" aria-label="Next page"><i class="fa fa-angle-right"></i></a>

The characters "测试章节" were badly encoded.

What's more, this is not an issue on Linux OS environment.