Quark subtracts one item from every block item stack that a block drops, this behaviour is probably intended for situations where the crop and seed items are separate like wheat, but for crops like carrots where the loot table defines multiple stacks of seed items to be dropped it causes lost yields.

For example with carrots, the loot table drops a stack with 1 carrot and then another stack with a random amount between 1-3. Simple harvest will consume the first stack's carrot then one from the second stack, effectively using 2 carrots to replant 1 crop.

Simple harvest should probably stop consuming items after one is taken.