A practical workflow
Label both actions
Use distinct captions for payment and feedback. A small colour change alone may not explain the difference.
Separate the placement
Put the review invitation where it will not interrupt payment. Make the optional nature of the feedback request clear.
Test the staff explanation
Ask staff to point out the correct code without directing customers toward a rating. Check that first-time visitors understand the distinction.
Avoid this mistake
Avoid displaying two unlabelled QRs side by side under the same business logo.
What to check
Ask a test visitor which code they would use for payment and which for feedback.
Test the whole physical journey
Check both the printed code and the page behind it. A successful scan is only the entry point: the customer still needs to recognise the business, describe an experience and understand the Google handoff. Use the final material under ordinary lighting. Keep a copy of the approved artwork so a replacement does not accidentally introduce a different destination.