QR code doesn't appear when canvas fingerprinting is blocked
It seems that when browsers or plugins block fingerprinting by canvas renderings, they block toDataUrl()
on the canvas element. That is the method that exports base64 encoded png image data from the canvas element. This is also what is used by jquery-qrcode to add the QRcode to the page. Which is actually not necessary the only feature it adds is that you download the image from the webpage, but it's a pixel for pixel copy of the canvas version. I checked and can't disable it with an option. We could do a PR but there are so many old open ones on the project that I think it will never get merged.