To get there, you'll need to go from a room with a name starting with 3:<something>. Not spoiling the exact room, but blink around and you'll find a place you haven't beaten yet!
thanks for replying so quick! i found it, and beat the game (finally lol). super cool concept, and as pretty much everyone else has said, the qr codes are super original! the whole thing: the art, the music, the mechanics and the codes make for a game that really stands out from the rest. severely underrated. thanks again for the tip!