UI icons are not displaying correctly on Firefox / Firefox Nightly

[KirbyJoe]

💡 Summary

I was browsing Misskey.io on Firefox Nightly, but I noticed that the user interface icons are not displaying correctly. I also tried accessing other Misskey instances such as Misskey.design and KindWorld, but the icons are still not displaying correctly. When I browse Misskey instances on Chrome (which is my default browser), the icons are displayed correctly.

🥰 Expected Behavior

The icons should display correctly as shown below (screenshot from Chrome):

🤬 Actual Behavior

The icons are displayed as garbled text/mojibake (screenshot from Firefox):

📝 Steps to Reproduce

1. Access to any Misskey instances with Firefox

📌 Environment

💻 Frontend

• Model and OS of the device(s): Alienware Aurora R7, Windows 10 Pro 22H2
• Browser: Firefox Nightly 120.0a1 (2023-10-11) (64bit)
• Server URL: misskey.io, misskey.design, misskey.kindworld.one
• Misskey: 13.14.2-io.10 (Misskey.io), 2023.9.3-md.3 (Misskey.design), 2023.9.3 (KindWorld)

[CyberRex0]

https://github.com/webcompat/web-bugs/issues/118081

[futchitwo]

10371