Use a VM (VirtualBox) or a disposable Windows Sandbox without network access.
The mod forces a desynchronization, where the client thinks an item is in a chest, but the server thinks it is in the player's inventory, allowing for a temporary duplication until the server forces a re-sync. File name- Dupe-Trigger-Mod-Fabric-1.20.1.jar
To help you safely investigate or manage your Minecraft setup, let me know: Use a VM (VirtualBox) or a disposable Windows