I wonder if there is a Unicode character symbolizing a QR code?
I think I have seen that some time ago as an character but I can't remember if it was a custom font or an official Unicode character.
I bet you mean a unicode character. There is no such thing like a utf-8 character. You can encode a character in utf-8. I never heard about that unicode codepoints cover qr codes. With private codepoints as well as the appropriate font it's of course possible.