Via [url=https://steamcommunity.com/games/CSGO/announcements/detail/657081807721726695]the Steam Community[/url]:

[quote=Valve][b][u]MAPS[/u][/b]
[b]Ancient[/b]
- Reverted "house" roof decorations near CT spawn.
- Restored the ability to wallbang the plywood in "cave".
- Various changes to the daytime soundscape.
- Fixed items getting stuck behind the rubble pile on T side of B.
- Player clipping adjustments.

[b]Shoots[/b]
- Player clipping adjustments.

[b]Ancient and Shoots[/b]
- More Ancient and Shoots source content is now available for community map makers in maps/editor/zoo/ancient_zoo.vmap.

[b][u]MISC[/u][/b]
- Fixed knife slashes applying a 'dry' attack decal on wet surfaces.
- Fixed a case where clients would mispredict shots if the attack button was held across round respawn.
- Fixed a case where the viewmodel would stick to the camera when cl_lock_camera was set.
- Fixed a case where fullscreen windowed mode wasn't offering resolutions with extreme aspect ratios.
- Fixed a case where fullscreen windowed mode wasn't actually stretching to fill the screen.
- Fixed a case where relative mouse motion was incorrect on Linux.
- Various stability improvements.[/quote]

Rumor has it:

- Size is close to 1.5 GB (with Workshop Tools installed)