That's the signal for filling recipe, not the barrel.
11-15-2024, 23-01-59.png

The barrel without the icon is the one you're looking for:
11-15-2024, 23-05-11.png


I use this to set a recipe only for items that do not have a full stack. If I set two signals for one recipe, then a new scheme is ...

When the mode - Stack size is enabled, the stack size of barrels is not sent