The main change in the new update is the ‘Quick Play’ mode, which is more accessible and less annoying.
For example, this is how it was before:
Now we don't need to make the extra steps, so:
Before the updates, interactive objects did not contribute to gameplay and were used for lore and atmosphere with zero impact on how you play the game.
Now, interacting with objects can affect the mission; for example, you might find a button that opens a hidden passage when pressed.
New Weapons (free for all players)
New Equipment (free for all players)
New Attachments (free for all players)
DLC owners will get a new gameplay mechanic, which is "lethal gas", so you will have to use a gas mask, additional exclusive cosmetics, and access to 3 unique missions:
(Note: Free in multiplayer if the lobby host owns the DLC)