It looks like one of Valve's night-time janitors made an oopsie by including certain details about the "secret" Counter-Strike update in the latest patch for DOTA 2.
Valve released a massive (and ultimately unsatisfying) patch for Dota 2 after the equally underwhelming Lima Major ended. The update brought several balance changes to Valve's premiere MOBA as well as the highly anticipated hero, Muerta. But, dataminers found something else as Valve focused on "updating [the game's] models to a newer format known as ModelDoc."
GabeFollow broke the news about the "hidden" files on Twitter and fans have already referred to it as the "biggest CS:GO leak on Source 2.
The leaked files included the old "Zoo" map, cases, spray kits, keys, and stickers, which the change list notes are "listed on the Source 2 Developer Community Wiki."
This and the fact that it comes soon after a whistleblower revealed that CS:GO 2 is coming soon has sent fans into a frenzy.