What I expected to happen:
Hoppers would put all the items in the bottom chest because of downward hopper priority.
What happened:
Hoppers split items between the top and bottom chest
How to reproduce:
1. Place 2+ chests vertically
2. Place a hopper chain straight down pointing into the chests.
3. Add items to the top hopper of the chain
4. The input items will split between the top and bottom chest of the stack. (note: If 3+ chests, the middle chests receives none, top and bottom both receive half)
Duplicate of MC-149940.
"Downward priority" is only a thing if you don't put more than one item into the top hopper at once.