https://www.gamespot.com/articles/ps4s-exclusivity-window-is-shorter-than-usual-for-/1100-6461928/

Activision has confirmed that the post-launch DLC for Call of Duty: Black Ops 4 will be coming to PS4 first before also launching on Xbox One and PC. That's no surprise, as the PS4 has received early access to DLC expansions on every Call of Duty game since Activision first partnered up with PlayStation for 2015's Call of Duty: Black Ops 3. However, this time the PS4 has a much shorter exclusivity window.

For Black Ops 4, Activision has announced that the PS4 will only have a one week head start on the Xbox One and PC when it comes to playable post-launch content. This includes all seasonal events, as well as new specialists and maps for multiplayer. The Nuketown multiplayer map will come to all platforms in November, followed by new specialists in December. Past Call of Duty games have given the PS4 two to four weeks exclusivity on certain updates. With that window shortening so dramatically, it suddenly doesn't hurt as much to be pre-ordering Black Ops 4 on Xbox One and PC.