Via the Steam Community:

PREMIER

• Updated the map selection process to give players more opportunities to play maps they've been learning.
• Map selection process:
  • Team 1 picks one map
  • Team 2 picks two maps
  • Team 1 picks a final map.
  • One of the four maps will be randomly selected and the match will begin.

RUSH

• Rush is a fast-paced queued 3v3 game mode.
• Players battle through a series of battle arenas to reach the opponent's castle and win the match.
• Battle arenas are randomly selected for each match, so no two matches are the same.
• Control the tower when you eliminate the enemy team (or time expires) to win the round.

GAMEPLAY

• Players can now reload silently (but slowly) by pressing and holding the reload key.
• Un-scoping a sniper weapon no longer produces a sound.
• Globally increased visual clarity and improved fidelity of bullet impact decals.
• ammo_grenade_limit_total setting now also enforces the total number of grenades a player is allowed to purchase in a round.
• Chickens now take damage from the Zeus x27.

SETTINGS

• Crosshairs have been updated to be resolution independent.
  • A new "Crosshair/Scopes" tab is available in the Settings menu, and includes updated crosshair settings.
  • Added new crosshair styles
  • Updated the default crosshair to "Dynamic Quad," which better represents weapon accuracy.

ENGINE

• Updated engine code to the latest version of Source 2.

MAPS

Ancient

• Fixed holes in world in Long A Main Hall.
• Adjusted door geometry and grenade clipping inside Jaguar.

Cache

• Some gap fixes and clipping adjustments around the blue doors in Mid.

Mirage

• Reinforced scaffolding by balcony in A site.

Train

• Blocked pixel gap in crates on bombsite A.

MISC

• Added ability to set a "Clan Tag" for players who are members of Steam Community Groups. You can adjust your Clan Tag from your Player Profile.
• Added support for applying stickers to C4.
• The Starjunk 95, Industrial Sunset Memories Music Kit is now available for purchase in standard and StatTrak versions through the STORE tab.
• Halftime scoreboard stats should now fully reflect the results of the previous round.
• Fixed a case where players could avoid a kick ban.

WORKSHOP

• Added "minimap_volume" entity which enables a custom minimap image when a player is within the volume.
• Added "sky_camera_volume" and "sky_camera_volume_target", which enable custom location-specific skybox rendering.
• Added "point_deathcam_bounds" entity that constrains the player death camera.
• Added "env_shake_volume" entity that allows camera shake only within a specified volume.

SCRIPTING

• Added CSRadarPoint entity.
• Added CSObservablePoint entity.
• Added AddTeamMoney API method.
• Added OnPlayerTeamChanged callback.
• SetDialogVariableString now accepts a localization string.

Rumor has it:

• Size is close to 5 GB (with Workshop Tools installed) - data capped users should take action now