Roblox should take the #1 spot on this list by a mile. puts Roblox at 229K active players today which is hilariously inaccurate. So they're off by a factor of 7 here and this isn't even close to the most egregious error.
They claim that New World has 987.99K active players today (December 3, 2021), but a quick look at Steam Charts shows that New World peaked at 131,544 today. The relative rankings and the active player figures are not at all accurate. The problem is their data is so wildly inaccurate that their daily rankings are totally useless. The website purports to rank the top 20 of the most popular MMO Games by active players and total population on a daily basis.