After querning any item that already exists in the player's inventory, including food items that match one another precisely, then shift right clicking the edge of the quern to retrieve the items without opening the quern GUI, the quern's output item(s) will be placed into an empty slot of the player's inventory or hotbar. E.G. when retrieving 8 redstone dust from the quern while 8 redstone dust are already in the player's inventory, you'll wind up with 2 separate stacks of 8 redstone instead of 1 stack of 16 redstone.

As of v0.27.6.107.