After installing the extension in Firefox, it is stuck on generating tokens, with no obvious error message or feedback. Also in this state, the Kagi webpage is no longer accessible.
It can apparently be fixed by selecting "off" in the extension popup and then turning it on again. While the extension was turned off, I also visited the Kagi webpage to check if it works again, so maybe this also had an impact. I have had this happen on two different computers.
Firefox version: 152.0.6
Operating system: Windows 11

The extension should work immediately after installing it.