Why does scanning my QR code open a Google sign-in or registration page instead of the review page?

The reason you encounter the log-in screen is that Google requires users to log in to leave a review in order to prevent fake reviews. For users who are already logged into Google on their phone, they will already be signed in and will directly leave you a review.

The way the URL works is that it first routes through our server so it can identify which business the QR code is linked to. Once the initial setup is completed, every future scan will redirect users straight to your business review page.

This is the desired behavior to send your customers directly to your review page. There is no way to deep link into the Google Maps app directly to the review page, it will only go to your business page without opening the review page.