I'm not quite sure what you're getting at, but Apple knows where the barcode is already. The data for the barcode is given as text, apple draws the barcode.
Maybe what you want is for the screen to support turning up brightness for just one part?
Maybe what you want is for the screen to support turning up brightness for just one part?
That’s what their comment is asking for, which is why they mention HDR displays which are already common on Apple products.
From another comment in this thread, you can see a proof of concept using the HDR video workaround that works on any recent iPhone (or MacBook Pro): https://dt.in.th/HDRQRCode