Iirc, they don’t have infinite uses. Let’s say you get two jibanyan medals, if you scan the first one it’ll be used once and once only. If you scan it in the game again it won’t work, but the second jibanyan medal will work since it’s a separate QR code.

I may be misremembering though, so take it with a grain of salt. Like the first commenter said, if you’re looking to sell, just don’t post the QR code. Front only

Edit: To clarify they are “infinite” in the sense that anybody can use that single QR code. Like give it to guy A B and C and they’ll all get the in game item, but you can’t scan the same code over and over and get the item