Firefox supports several locations for extension buttons. For things that relate to the current page, e.g. translations, one can put the button in the address field. This is called a "Page Action", see
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/user_interface/Page_actions.
You can see that in my address field there is "6" (IPv6), an RSS add-on, and a bookmark button.
Currently the built-in translator is located in address field, but Kagi Translate is located with the "miscellaneous" extensions, e.g. VPNs and Password Managers.
I think it'd be more intuitive for Firefox users if Kagi Translate was in the address field like the built-in translator.
