Originally Posted by
motocrossmann
There is nothing special about a QR code, it is just a series of letters/numbers.
Slight clarification: it depends on the entity generating the QR code. The payment-related ones (e.g. Chase Pay/Walmart Pay) use different letters/numbers every time the user requests the code to be displayed, so any hand-generated one would likely only work once--if that.
That said, I don't think Apple Wallet supports being able to regenerate the QR code every time the pass is brought up.