Treyarch recently held a Call of Duty: Black Ops 6 direct that came with the information that content from previous CoD games, including Modern Warfare and Warzone, will not carry over.
You may have dozens of operators, skins, and gun camos from recent Call of Duty games, and all of that will stay in the past once Black Ops 6 drops. It’s a move that’s certain to enrage some players, but Treyarch has a justification for the decision.