In Zynga Poker Jump Poker was a game mode that players used to be able to play on the mobile application version of the game. In Jump Poker, you can fold your hand at any time and move to a new hand right away. This change leads to a very fast-paced game, and things only slow down when you are forced to play the big blind.
At the time there were two separate versions of the game. A web browser version that could be played on Facebook and Facebook game room and the mobile version of the game. Zynga merged both versions of the game, and the mobile version of the game is the one everybody plays. Right before this merge, Zynga removed Jump Poker from the game.
Why was Jump Poker removed from the game? I have no idea. One would have to contact Zynga to ask.