Plunder has disappeared from Warzone 2, mere weeks after it was reintroduced. But don't worry as it's coming back sooner than you would think.
Warzone 2 Season 3 Reloaded launched yesterday and brought along the new Warzone Ranked mode and the new DMZ Koschei Complex experience with it. But amidst all of the excitement of these new additions, Activision took Plunder out of Warzone 2. The highly requested Plunder mode from the original Warzone made its return to the game less than a month ago and already it's been bumped out of the in-game rotation, presumably to funnel more players into the Warzone Ranked beta.
Currently only the Warzone Ranked beta (which is only available as Battle Royale Trios at the time of writing), Solos and Quads Battle Royale, and finally the full batch (Solos, Duos, Trios, and Quads) is available for Ashika Resurgence according to info posted on the Call of Duty Blog alongside the Warzone 2 Season 3 Reloaded patch notes.