Hey, I have a server with friends running Paper 122 for 1.14.3, plugins: AuctionHouse-1.7.6, ChestShop, EssentialsX-188.8.131.52, LuckPerms-Bukkit-4.4.1, Shopkeepers-2.7.2, and Vault.
If I leave the server running for about a day, players will become able to pickup items in their inventory, and have a copy held and another in their inventory. I can’t find any events causing this. This effects players server wide. Not sure if this is a plugin issue or a Paper issue.