“GG” is supposed to be a gracious admittance of defeat, and is considered in many circles to be highly insulting if the winner says it first.
You can read more up about the origins here: ~GG | Know Your Meme which has a nice write up about it. In Korea, in fact, if you play professional esports like Starcraft and you say GG first as the winner, you can even be fined by the leagues there.
So, being patronizing by saying it as the winner is nothing new. It’s 20 years old now.