to reproduce:

1. install the mod
2. give yourself 44 apples
3. die
4. collect your grave while having 36 apples in your inventory

• now you have 80 apples in one stack

Expected behavior
64 apples being in one slot and 16 in another

Desktop (please complete the following information):

• OS: windows 10
• Minecraft Version: 1.19.2
• Version: 1.4.9

Additional context

• We were playing on a server
• Fabric 0.14.21
• Cloth Config version 8.2.8

Screenshots

So I'm using a vanilla method that I thought would find a slot two stacks can merge. But what seems to happen is that the method only checks if 1 item of the inserted stack can merge with the existing one.
I'll have this fixed after some time. For the moment I don't have a lot of time to work on the current releases of the mod, as all of the little modding time I have goes into rewriting and improving the mod for 1.20.
Thanks for reporting this though. I have seen this before but I didn't realise until now how easy it was to actually reproduce it lol