Via [url=https://steamcommunity.com/games/CSGO/announcements/detail/529856292184915972]the Steam Community[/url]:

[quote=Valve][b][u]MAPS[/u][/b]
[b]Ancient[/b]
- Restored some grenade lineup visuals.
- Misc clipping fixes.

[b][u]ANIMATION[/u][/b]
- Fixed issues with the classic knife's inspect animations.
- Fixed the deploy for the Stiletto knife.
- Fixed the deploy for the Butterfly knife.
- Updated Talon knife inspect while 'fidgeting' to be more responsive.
- Adjusted Flip knife animation when inspecting immediately after deploying.
- Adjusted Bayonet knife animation when inspecting immediately after deploying.

[b][u]MISC[/u][/b]
- Fixed a performance regression when creating bullet impact effects.
- View angle velocity now affects spectator target viewmodels the same way it affects local player viewmodels.
- Fixed a case where looping weapon inspects weren't networking to spectators.
- Fixed a bug where matchmaking was avoiding servers playing the nighttime version of Ancient.
- Removed legacy sprite-based shell casing fallback particle effects.
- Fixed case where overlapping smoke clouds would prematurely extinguish molotov fire.[/quote]

Rumor has it:

- Size is ~900 MB (with Workshop Tools installed)