I decided to just look at the numbers myself and I'm not sure where the author of the article got "68k in May" from. The average for Jan - May 2022 was around 90k. The average count in 2019 was 68k and has been steadily climbing ever since. But if we change the numbers to what they are:
= May with 90k average
+ June and July with 140k average
- Aug and Sept with 115k average
I didn't include October because of Scream Fortress and since we don't have November yet, it's hard to know if that slight increase in players is purely for the event or if some plan to stick around afterwards. Regardless, we can say there was a definite and consistent increase from May 2022 by at least 25k players. The biggest problem when talking about any of these numbers is that we still don't know how many of the numbers include bots, traders or idlers which always make it really, really hard to refer to Steam Charts when talking about if TF2 is thriving or dying.
TF2 could've gotten a boost because of an update around May that made it harder for bots. TF2 could've also gotten a boost because it was summer and school was out and those numbers were going to rise regardless of an update. Those numbers could also be because 11 new unusual effects were released in summer and a bunch of traders unleashed their idle bots so they could farm and trade for keys and unlock crates. It could be all three, I don't know.