Recently if you use Discord and you are part of a big server you know about this most likely.
For those who don't but are curious what is going on let me explain and also whats going on in the back end of this scam. First off it is NOT a hack, it is a scam. What's going on is that people are getting these QR codes on there screens, copying them, then posting them in either DMs or publicly in Discord servers. These messages can usually go from "free nitro" to maybe unlocking features, or something else Discord related. Either way they will send a QR code. Best course of action is no not scan it.
Boring scary part out of the way, let's get into how the scam works. It gives you a false sense of hope, because those who see it think "Oh it is Discord related" and scan it with the QR Code scanner built into the Android and iOS apps, with that the scammers got your Discord account. How? Well the QR Code reader reads login codes to make logging into other devices easier. This was a feature recently sent out sometime recently by the Discord team themselves with the oversight that people could use this to steal accounts which can be used to log into. The QR code is used to log in and can only be used if you are logged in with a mobile device. Some people might not know this feature and not know it is dangerous so is why it has been working decently well.
Do not trust random QR codes anywhere, even if it connects to the same service that you saw it on.