Then your qr code only works if the url shortener stays online.
In many cases its wiser to roll your own permanent shortened urls so you aren't beholden to a third party service.
In many cases its wiser to roll your own permanent shortened urls so you aren't beholden to a third party service.
If you care about QR code size, you should use URL shortener service which you can program in whatever way you need.
So I don't think that's major restriction.