The kagi QR code login works through a link scanned from a QR code with the camera opening up in the browser - this is somewhat inconsistent with other apps (e.g. discord, steam) where both a direct link from camera and an in-app QR code scanner will perform the login. It took me a bit to realize that I had to simply scan it as a plain QR code for the link.
I believe this also currently limits the logins when the user is not logged-in in their mobile browser and only in the app
