The ID Blackjack refers to the specialist:
Once a well-connected 54I fixer, Danny Li narrowly survived a disastrous meeting that he brokered between Winslow Accord agents and the organization's leaders through the use of a recently acquired Rejack unit.
Deeming that they had suffered too many losses already, the enforcer, Seraph decided not to execute him for his part in the deaths of Min and Xuilan Goh, stating that they needed all of the remaining strength in order to rebuild.
Blackjack now operates as a mercenary, restoring his reputation, and bringing glory to the clan; all the while salvaging up new stock from the spoils on the battlefield.
- Danny "Blackjack" Li - callofduty.fandom.com