Via CS:GO Blog:

MISC

• Bomb logic now runs every tick when it is close to exploding or being defused, addressing some rare cases where an extremely close defuse would still result in the bomb exploding.
• If a bomb would both explode and be defused at the same exact time, it will now be considered defused.
• Prime accounts will now receive a warning in a Competitive lobby when they enter matchmaking with other Prime accounts whose Trust Factor may impact their matchmaking experience.

GAMEPLAY

• General adjustments to ambient sounds:
• Increased resolution and character of reverb effects to better reflect surrounding map geometry
• Small mix adjustments
• Improved vent destruction sounds and increased audible distance.
• Added a new hitbox type for necks and applied it to the existing neck hitbox on character models. Bullets that penetrate the neck into the head will now count as headshots. This should make it more intuitive to tell when an attack from behind will result in a headshot.
• Fixed ‘use’ key to more reliably pick up weapons on the ground and to not drop the active weapon if a replacement weapon cannot be picked up.

MAPS

Nuke:

• Optimizations for low settings
• Blocked visibility between silos inside A site
• Ported over ShortNuke gameplay changes:
• Removed Toxic
• Vent no longer connects directly to B site, but has another exit close to double doors
• Pushed new corner boxes on B site further back to prevent headshot angle towards ramp
• Added solid background to yellow crane inside B site
• Smoothed out some player movement

Overpass:

• Lowered volume of ambient sounds in Overpass
• Added grenade and player collision to fence cage near construction
• Removed spooky shadow fading in when approaching T main entrance to B site