Are the QR codes and feedback page different for each business?

Yes. The QR codes and feedback page are different for each business.
In practice:

• Each business has its own review request link.
• The QR codes you download for a business point to that business's link; if you download QR codes for another business, they point to that other business's link.
• The feedback page (image, language, white-label logo) is configured per business in "Feedback page"; when you switch businesses in the selector, you'll see and edit the configuration for the selected business.

Don't share a link or QR code from one business for another: customers would land on the wrong business's review page.