If I right click a 50000 stack and put it in a box, it will split into 10000. This is how it should be
But if I put a 50000 stack into the backpack, it stays that big, I don't want that.
I use
StackSizeController and ChestStackMultiplier
What do I have to do so that this also works for the backpack?
I would be grateful for help

The Chest Stack Multiplier plugin has a config option for Backpacks. If you experience any issues with that, report them to Chest Stack Multiplier dev.

WhiteThunder

The Chest Stack Multiplier plugin has a config option for Backpacks. If you experience any issues with that, report them to Chest Stack Multiplier dev.

I will, thank you