In Minecraft Bedrock, there is a bug where you can dupe items, the player opens up their inventory then grabs 65 items or something, then leaves and joins.
This mod fixes it. that's all, just download it and add it to your world, no expirements needed, nothing. You can suggest more dupe methods in comments which I will possibly fix.
How does this work?
Whenever a player joins, it tests for the item in their cursor inventory, and if the item is a complete stack the mod will clear that item and throw 1 item of that in the ground, simple really.