When you use pickup upgrade, if you acquire a large amount of items, the items are replicated.

To Reproduce
Steps to reproduce the behavior:

1. Equip the backpack and pickup upgrade
2. Drop 1024 redstone and pickup
3. See a lot of redstone

Expected behavior
Only 1024 redstone

Screenshots
https://drive.google.com/file/d/1fNEUHG1GhHTnnyYBbglq9rWPKZz-j-2Y/view?usp=sharing

Versions
Minecraft 1.20.1
Forge 47.2.1
sophisticatedbackpacks-1.20.1-3.18.65.935

I found a clearer condition.
It occurs when used with the staaaaaaaaaaaaaack mode.

I am closing this but feel free to reopen in case they have a clear indication my mod is at fault

Is that some kind of mod that chnages max stack size of stacks that can exist in the world? I can't find anything on that. Anyway if a mod changes max stack size of item entities you want to report to them first as its very likely they are not handling that correctly. In this case very likely incorrectly triggering/handling player pickup event