The bug
When a Crafter attempts to output multiple items at ones in a Composter, only one item will be composted and the rest will be dropped as item entities inside the Composter.

• In 21w45a, the Composter composted all items as one, but since 21w46a, it composts only one item and drops the rest. This is probably related to MC-265950 (which properly fixed a similar issue, but only on Chiseled Bookshelves)

To reproduce:

1. Place a crafter facing downward directly above a composter
2. In the crafter, put a stack of cocoa in the top middle slot and two stacks of wheat in the two top corners (this will output 8 cookies)
3. Place a button on the crafter and press it
4. Open your debug screen (F3)
5. Look at the "level" state of the composter
   See if the composter went up more than one level (normally 8 cookies would raise it a few levels)
6. Switch to spectator mode (F3 + N)
   See if there are cookies inside the composter

What I expected to happen was...:
The composter composting all the cookies at once

What actually happened was...:
The composter could only compost one cookie and dropped the rest as item entities.