[MC-253076] Allay duplicates Items when its NBT data is updated every tick

When continuously using the command:

/data modify entity @e[type=minecraft:allay,limit=1] Motion set value 0

The Allay will try to throw the matching item at you but instead duplicate it. This appears to continue indefinitely. It also appears to only work with stackable items.

Attachments

2022-06-15 00-20-20.mp4

Comments

Avoma 2022-06-15T11:00:06Z

I can confirm this behavior in 1.19. This issue can be seen when the allay's NBT data is updated every tick and isn't just exclusive to updating the "Motion" tag constantly. Here are some steps to reproduce this issue.

Steps to Reproduce:

Summon a repeating command block that will constantly set the closet allay's "Motion" tag to "0".

/setblock ~3 ~ ~ minecraft:repeating_command_block{auto:1b,Command:"data modify entity @e[type=minecraft:allay,limit=1,sort=nearest] Motion set value 0"}

Summon an allay and give it a diamond.
Throw a diamond on the ground and allow the allay to collect it.
Wait for the allay to return the item to you and observe how it duplicates the diamond and gives you multiple of them.