Some just put that there. They have said they expect to go into Early Access sometime in 2020. December 31 is the last day of 2020.
It doesn't mean that is the date. EA could be before that date, or if things are delayed further by the social distancing, it could be after. Also, that is just a wiki page not an official Larian Page.
Right? its just funny cuz when i am checking something so much, the moment something is different or changes I notice immediately lol. Here's hoping the STADIA event on tuesday brings some more good news..