I highly recommend adding a trading room for OPPvP just like the one with have in KitPvP 2. It’ll help the community to trade/sell items without getting killed or getting the items robbed from them in the process of trading/selling.
Please use the official KitPvP/OPPvP thread to make a suggestion for the upcoming OP PvP release. We will not be making major modifications to the legacy gamemode and will only be considering suggestions for the legacy gamemode that involve patching bugs. https://www.mineverse.com/threads/official-kitpvp-oppvp-suggestions.142429/ (We're already adding a special /trade plugin in the new OP PvP).