Via [url=https://steamcommunity.com/games/TF2/announcements/detail/4520017657931497817]the Steam Community[/url]:

[quote=Valve]- Reverted BLU Scout pants fix because it conflicts with too many existing cosmetics
- Updated the Fleet Commander again to fix import problems from the previous update
- Updated the Phantom Plague and Haunting Haze Unusual effects to fix sometimes spawning away from the player

- Updated cp_freaky_fair
- Fixed issues related to the gamemode logic
- Reapplied check that was mistakenly removed to check if the player is actively buying upgrades in a station or not
- Implemented new custom system to refund upgrades to hopefully address inconsistencies both in-round and across rounds
- Implemented logic to handle mismatches in recorded vs actual currency values when leaving the upgrade trigger and having not accepted de-bought upgrades
- Reverted code to do with Ghosts and Sentry busters to fix bugs related to their effects not de-applying
- Implemented a way to force kill players to address edge cases where you could survive as the sentry buster past their explosion (Thanks MilkMaster!)
- Improved the logic which checks if you can apply a new potion effect to yourself to address bugs where effects can overlap
- Fixed sniper and demo shields not having their upgrades cleared
- Fixed canteens not having their values cleared when refunding whilst not equipped
- Increased the height of the skybox
- Increased last point capture time from 6s to 7s
- Changed some clipping to stop giants from building on roofs
- Smoothed out a divot (Thanks Midnite!)

- Updated zi_atoll, zi_blazehattan, zi_devastation_final1, zi_murky, zi_sanitarium, and zi_woods

- General
- Re-encoded all Zombie Infection sound effects as .WAV
- This fixes issues with sound effects not playing correctly and spewing errors in the console

- Bug fixes
- Fixed a bug that caused Sniper's Spit Pool to deal much more damage than intended
- Fixed a bug that caused team names to not display correctly when playing on mp_tournament mode
- Fixed a bug where Engineer would sometimes scream like a charging Demoman while throwing an EMP Grenade

- Zombie Changes
- Sniper's Spit Pool damage vs Survivors no longer stacks when standing in multiple zones
- Zombie Heavy is no longer immune to Critical Hits
- Zombie Heavy's max health raised to 525 (from 450)
- Zombie Pyro's max health raised to 250 (from 175)
- Zombie Pyro now drops a medium health kit on death

- Survivor Changes
- Crossbow weapons no longer have a flat damage multiplier against Zombies
- The B.A.S.E Jumper can no longer be deployed if you are one of the last three survivors
- Jumper Weapons can no longer store reserve ammunition

- Updated zi_murky (additional changes)
- Added more respawn room triggers around the new spawn zones[/quote]

Rumor has it:

- Size is ~80 MB