Utf-8 caracter in page seems to break anchor

[gsemet]

Hello . I use confluencebuilder with MyST and I have some fancy utf-8 characters in my document title, such as:

overview.md:

# 🌐 Overview
...

## 🧩 Features

...

On HTML rendering, no pbl, the link set in the mini-Toc

are correctly set to

overview.html#features

But on the confluence builder, the ToC have this link

... pageId=612020492#🌐Overview-🧩Features

In the HTML page the anchor looks like

<h2 id="🌐Overview-1.1.🧩Features">1.1. <a href="#Agpkg0.x1.🌐Overview-id2">🧩 Features</a></h2>

Not sure if this comes from the weird utf-8 characters, but this anchor does not work.

Their is a "1.1" number in the anchor that does not appear in the Toc

The toc is created by:

:::{only} confluence
```{contents} Table of Contents
  :depth: 3

---

:::

Any idea?