Via HLDS:
Valve- Fixed corrupt textures that were appearing for some players
- Fixed crashes that were occurring for some players with 3GB or less of RAM
- Temporarily removed texture memory optimizations for players on Intel Integrated GPUs
- Fixed a client crash related to the backpack
- Fixed a bug where mini-crits were overriding full crits
- Fixed "Sort by Date" sorting in the wrong order in the backpack (design is to sort with newest items in the front)
- Fixed the Invasion Unusual effect "Subatomic" being off-center
- Fixed not being able to put cosmetic items from the Gargoyle Collection onto the Steam Community Market
- Fixed missing kill icons for the Invasion weapons
- Fixed the "Win a Bumper Kart minigame" Merasmission objective not triggering in the event of a team wipe
- Added a "Batman" tag for Workshop submissions for the Arkham Knight Contest
- Fixed missing Quickplay images for Mannpower maps Gorge and Thunder Mountain
- Updated PASS Time to fix not seeing the Halloween version of the Jack while it's being carried by a player
- Updated The Infernal Impaler, Courtier's Collar, Iron Lung, and The Bearded Bombardier
Rumor has it:
- VPK contents diff: https://github.com/SteamDatabase/GameTracking/commit/92e3db78a0f1e5368aa8d37731cb9d37c6115730
- Some deep level stuff: https://github.com/SteamDatabase/GameTracking/commit/d36e7233b1d1c0ffdc2b344562ab0772b6f94117
- Size is ~45 MB