A verified device relies on two things: the device and the browser you use on that device. If you complete the account verification steps on a device using your usual browser, that device and browser will be verified.
If you log in on a different browser on that same device (or clear your usual browser's cookies), you’ll need to verify again. If you log in on a different device altogether, you’ll need to verify again.
For example, your laptop, desktop, and phone all count as separate devices. If you use multiple browsers (Chrome, Firefox, Safari, Edge) on the same device, those will also be counted as separate devices.