When we flew to and from Spain you also had to attach your vaccination code to the locator form. I just really wouldn’t take the risk of a faked document.I haven't been anywhere that has scanned it yet however - we flew from and back into Dublin to travel to Spain and they are only doing spot checks (EU has much more open borders than travel into and out of UK). In Spain they made a photocopy of the vaccine cert at my hotel but again didn't scan the QR code.
In saying that, I pre uploaded all my covid paperwork with ryanair so they could have been checking it more formally and I just didn't know!