Edit history for this question shows that a moderator rejected the edit four months ago (for reasons I also agree with), but this edit is approved few minutes ago by OP so it stands approved (See How do suggested edits work?).
The approved edit brings about a fundamental change to the question, making the existing answers only partly correct and relevant. Someone visiting the question today (it is on the home page) may actually down vote the answers as they don't match the question body. It's another matter that the approved edit made changes to the body but not to the title of question.
I doubt if 7 years back when the question was posted, QR codes were a thing. Bringing that in the scope of question now, is meaningless.
To give another example, USB Type C charging wasn't around about four years ago. If OP of a question approves an edit that brings Type-C charging into the ambit, we would have a similar problem (if the question was posted pre Type-C days)
IMO, moderators should rollback the edit approval in this instant case. That's the easy part (hopefully moderators can do that based on this meta post, a cursory check threw up Rolling back a completely changed question)
How to ensure it doesn't happen in future is the difficult part since OP exercises similar power to that of moderator, in edit approval / rejection.