I assume it goes to a URL which is only valid between noon and 1pm. The QR code is probably scannable during a time period slightly wider than that, depending

I assume it goes to a URL which is only valid between noon and 1pm. The QR code is probably scannable during a time period slightly wider than that, depending on the time of year. It looks like the QR "statue" pivots to correct for the changing path of the sun across the sky, but the positioning doesn't have to be accurate to the point of working exactly from 12:00:00 to 13:00:00 local time. You can also add enforcement on the web server.