Player trading has been temporarily paused in Diablo IV after developer Blizzard was made aware of an exploit that was allowing players to duplicate gold and items through some simple steps.
The exploit involved two players initiating a trade, where one would put their items and/or gold in the trading slot for the respective player. This same player would then forcibly quit the game, and find their traded items back in their inventory after logging back in, while the player on the receiving end of the trade got to keep the items, too.
Since Diablo IV lacks any official trading hub, a market for items has been set up outside of the game through channels such as Discord, where this exploit has quickly shattered the established market pricing. One trade, which took place before trading was disabled, shows a crossbow being sold for a ridiculous sum of 30 billion gold. Since players are freely allowed to bid extraordinary amounts of gold for items (since none of it will be lost in a trade), many players looking to initiate legitimate transactions are being shut out.