Hello. Global Speed uses the TabCapture API for sound effects, which isn't available on Firefox.

Hello. Please submit the issue on Github. Since I cannot reproduce the issue myself, I'll have to ask you several questions.

https://github.com/polywock/globalSpeed/issues

Thanks! I would like to add global shortcuts, but Firefox only has limited support for them.

https://bugzilla.mozilla.org/show_bug.cgi?id=1411795

Hello! Valid concern, but it is being actively worked on. Currently testing the latest version on Chrome before publishing on Edge/Firefox. The Chrome Web Store had a June deadline for MV3 update, so I had to publish early, while for Firefox/Edge I plan to release July or August.