> That does not prevent them from putting up a warning message that says "You just scanned a code which will allow another device to read all future messages sent to you, and send messages from your identity. Are you sure you want to do that? And the button says "link devices", not "yes" or "no."

As an experiment, I just linked a device to my Signal account. After clicking "Link new device" in Signal, and then scanning the QR code, a dialog popped up: "Link this device? This device will be able to see your groups and contacts, access your chats, and send messages in your name. [Cancel] [Link new device]"

If I scan the QR code with Google Lens instead, it reads and displays the sgnl://linkdevice... URL but does not launch (or offer to launch) Signal.