It appears that Steam is continuing to skyrocket in popularity, as it has broken its record for concurrent players for the second time in 2021. The platform recorded 26.4 million users over the weekend which is an additional one million on top of the previous record. According to PC Gamer, the most popular games played during this period were Counter-Strike: Global Offensive, Dota 2, PlayerUnknown's Battlegrounds, Apex Legends.
These figures are pretty impressive indeed but it's worth noting that players don't need to be in-game to be registered as a concurrent user. If you have the platform open and you're browsing the Achievements or Community Hub for your favourite game then you will still be registered. The actual number of players in-game during this period was 7.3 million, which of course is much lower than the overall total.
You can check out some more interesting Steam statistics here.