QRPrint library characters limit
The code in the library truncates to 47 characters for some reason:

void printQR(String message) {

...

  // create QR code
  message.toCharArray((char *)strinbuf,47);
  qrencode();


The buffer is actually 116 bytes, oddly.

unsigned char strinbuf[116];


It's a little unclear why the limit of 47, or 116, was chosen.

You could try changing that line in qrprint.cpp to increase the number from 47 to at least 115.



Edit

After reading some of the comments, I doubt that will help. The QR code looks like it is generated into an internal array, which would have to have some size limits due to the amount of RAM available. The current array size is:

unsigned char qrframe[600];


That is already 1/3 of the available memory on a Uno.