Steam has surpassed previous concurrent user counts to a new height of 24,776,635 players today, per tracking site SteamDB. This new high beats records set in March of this year as Steam use skyrocketed amid global stay-at-home orders and lockdowns due to the coronavirus pandemic. This spike is probably more complex, but the onset of the winter season, renewed lockdowns in some countries, and the release of Cyberpunk 2077 are all likely contributors. Cyberpunk alone boasted more than a million concurrent Steam users earlier this week, a record for a singleplayer game on the platform.
The growing popularity of CS:GO also contributes a significant portion. Counter-Strike: Global Offensive first broke 1 million players in March with a peak of 1.2 million and just as quickly fell back down, but its average player counts have remained much higher than past totals throughout the year. It's now steadily climbing back towards the 1 million average players mark.
Contrary to records set earlier this year, the number of players registered as in-game by Steam is significantly lower than in March. While 8.1 million players were in-game in March, only 7.1 million were in game at the peak today. It's not immediately clear why that is, though some players do choose not to report what game they are playing, if any, to the network.