As of now, it’s uncertain when the feature will be back in the game.
Players of PlayerUnknown’s Battlegrounds will not be able to carry out personal item transactions for an indefinite period of time. This information was announced by the developers who stated that the feature will be back, but as of now, no exact dates regarding when the feature will be back has been revealed.
The feature is being taken temporarily offline because players have been misusing the system. The problem is that players are using this system to sell items using third party sites. Some players have been using this method so as to avoid having to trade directly through Steam. Since the personal trade in the game is free of cost, it helps these players cut costs by making use of such a method. Hopefully, the developers are able to find a suitable solution soon enough so that they can prevent an abuse of the system.
PlayerUnknown’s Battlegrounds is currently available on Xbox One and PC.