UTF-8 character in index.html is corrupted when building a WebGL project

How to reproduce:
1. Use a text editor to open “IN-124125_UnityWebGL_UTF8_Bug > Assets > WebGLTemplates > TestTemplate > index.html”
2. Observe the character in line 7 “CHARACTER:"
3. Open the “IN-124125_UnityWebGL_UTF8_Bug” project
4. Build the project for Web platform
5. In the build folder “index.html” file, line 7 observe the “CHARACTER:"

Actual result: The character stays the same “Ö”
Expected result: The character gets corrupted and displays the question mark symbol

Reproducible with: 2023.1.0a6, 6000.0.64f1, 6000.3.1f1, 6000.4.0b1, 6000.5.0a3

Reproducible on: macOS Tahoe 26.1, Windows 11 (by user)
Not reproducible on: no other environments tested

Note: After unzipping the project the character can appear as corrupted, instead use a hex editor and observe the hex values, the correct value is “D6”, the corrupted will appear as “EF BF BD”.