When connecting inventory trims to a large amount of inventory items, it makes you dupe items when dragging and shift-clicking the item. Doesn't dupe when connected with inventory cables

Using a modpack (Prominence II RPG)
Version 1.20.1

I had item vaults, but turns out it was the create belts, thanks!

Are you using the latest version of the mod?
Do you have any weird invertory touching the blocks? The inventory connector and trims connect all touching inventories. Create belts used to cause dupe bugs.