[Q] Why are keys now worth 3ref? Newbie trader here.

So I've recently started trading and I've checked prices everywhere, they all say keys are worth something around 2.66~2.88. I usually do my trades on tf2 outpost(and I've started like 2 weeks ago), and pretty much everyone is selling them for 3ref.

On their descriptions they say the price is firm because of 21 dec. What's on 21 dec? I'm guessing something related to Xmas, but what exactly? I have a lot of refs laying on my BP and I'm not sure if I should take their word and buy those keys for 3ref.

TL;DR: New trader. Checked prices for keys online, all are lower than 3ref. Everyone selling for 3ref. Something about 21 dec, don't know what.

PS: Pardon my english, it isn't my native tongue.