Sometimes hoppers soak up items at stack.

I observe this behavior in my monster farms.

Here I often kill 100 to 150 monsters in a very short time using a looting sword. The four hoppers in the ground are then not able to absorb all the items quickly enough and pass them on. That is normal.

It is not normal: If I manually empty an inventory slot of a hopper that 24, 42 or even more items get into the hopper, quasi instant.

I would expect a slow filling of the slot.

... not a big bug and not impractical, but you should know about it.