On November 19, CS:GO peaked at 1.13 mln players, breaking the record for this year. It happened after the patch with a few adjustments to weapon balance and a map rotation change. The developers removed the game's most iconic Dust 2 and brought the fan-favorite community map Anubis to the official competitive pool.
CS:GO has been prospering lately. Its monthly peak didn't fall below 1 mln since August, and the average player base was over 600k. The highest peak in history was 1.3 mln in 2020, most probably related to COVID, but typically the graphs do not spike that far. You need an in-game event operation or a big esports tournament to gather more players. The recent IEM Major Rio has not seemingly affected the player base at all.
The map change isn't even that big for a regular player, as it's aimed at professional play. Dust 2 kept its place in most of the modes, including competitive, and Anubis was available before the patch. The weapon changes have slightly nerfed M4A1-S and AWP.
It is not the first time when Dust 2 has been removed. In 2017, the developers reworked it to bring it back in April 2018. Anubis is the second community-made map in history after Cache to make it to the active map pool. This time, Valve has bought the rights from the mapmakers.