Weird. I've tested it with Firefox (on Windows and Mac OS). What OS are you on?

I think I'm running into the same issue, Windows 11 Firefox 109.0.1. The "ridge" of the reflection effect is stuck to the lower ~10% of the button, and completely dark, and the gold looks distinctly green.

Left is firefox, right is Edge (appearing, I presume, as intended)

[0] https://snipboard.io/AVU6zh.jpg

Working fine for me using Firefox 109 on Ubuntu 22.04.