Preliminaries:

• Shopkeepers version: <2.23.0>
• Spigot version: <Paper-1.21.1-40>

• I have checked that my issue/question does not get answered by:
  • The documentation.
  • The FAQ.
  • The Known Issues.
• I have checked all open and closed issues, but none seems to fit my issue/question.
  Looks like I have the same issue as #899.

Reproduction on a fresh and up-to-date Spigot server:

I was <not able> to reproduce my issue on a freshly set up and up-to-date Spigot server (currently <Paper-1.21.1-40>) with the latest version of Shopkeepers (currently <2.23.0>), with no other plugins and with no kinds of other server or client mods.

This is a very strange issue and I can't reproduce it in my local test server, even though I have the same plugin installed.
But in another server, it works fine as long as I remove the eco plugin
Everything seems to be normal when trading vanilla items
When you trade items that contain NBT (or is it Lore?), there is a display error, and although the trade has been successful, the exact target of the trade will not be displayed (nothing will be displayed on the right)
The plugin's configuration file is the default.

[21:26:48 INFO]: Server Plugins (76):
[21:26:48 INFO]: Paper Plugins:
[21:26:48 INFO]:  - HuskSync, MarriageMaster
[21:26:48 INFO]: Bukkit Plugins:
[21:26:48 INFO]:  - AntiEndermanMushroom, BarbatosStoryBook, BetterLogStrip, BetterRTP, BetterTridents, BlockLocker, BungeeTabListPlus, ChunkHeat, Chunky, Citizens
[21:26:48 INFO]:  CMI, CMILib, CodFrame, CoreProtect, CrateReloaded, DailyTaxEconomy, DeluxeMenus, DiscordSRV, eco, EcoEnchants
[21:26:48 INFO]:  FancyCropTrample, FastMinecart, GlobalMarketPlus, GSit, HeadDatabase, ImageFrame, InteractiveChat, InteractiveChatDiscordSrvAddon, InventoryRollbackPlus, *IronElevators
[21:26:48 INFO]:  ItemVoid, Jobs, *KeepItems, libreforge, LiteBans, Lootin, LuckPerms, MapModCompanion, mcMMO, MelonScoop
[21:26:48 INFO]:  Multiverse-Core, MyPet, NBTAPI, NyaaCore, OreBroadcast, PetMaster, PhantomSMP, PlaceholderAPI, Plan, PlayTimeTracker
[21:26:48 INFO]:  PlugManX, PremiumVanish, ProtocolLib, PvPManager, qsaddon-discordsrv, qsaddon-list, qscompat-ecoenchants, qssuite-limited, QuickShop-Hikari, Residence
[21:26:48 INFO]:  Shopkeepers, ShopkeepersStandardization, ShowItem, TheSearch, TrChat, TreeAssist, UserPrefix, Vault, ViewDistanceTweaks, WorldBorder
[21:26:48 INFO]:  WorldEdit, WorldEditSUI, WorldGuard, XConomy

See the https://github.com/Shopkeepers/Shopkeepers-Wiki/wiki/Known-Issues page in the wiki for a brief history of compatibility issues being fixed and then broken again. I will not spend any additional time in investigating compatibility issues with Eco.