Something which is becoming a regular occurrence lately: the Steam store broke its record for concurrent online users once again with over 26.4M online.
We can grab the data easily thanks to the excellent SteamDB resource, which showed that the new peak came in at 26,401,443 around 3PM UTC on Sunday. At the same time around 7.3M people were actually in-game too with Counter-Strike: Global Offensive clearly leading the player tables as usual with that game alone having well over 1M people.
At this point it can't really be put down to any one single thing, but the biggest factor is likely still the COVID-19 pandemic with many more at home. The overall numbers for Steam have been rising steadily again since July 2020 as shown by the "Lifetime concurrent users on Steam" graph provided by SteamDB.
It was also only recently that Valve announced they hit over 120M monthly active users too, and they have plenty of Linux-related work ongoing with some exciting stuff planned. We think we know what one of their plans might be too.