The Bug:

Goats will attempt to ram entities that are outside of the world border.

Steps to Reproduce:

• Set the center of the world border to your current position, along with making it 50 blocks wide.

/worldborder center ~ ~
/worldborder set 50

• Spawn a cow next to the world border.
• Shrink the world border so that the cow is outside of it.

/worldborder set 40

• Spawn a goat and wait for it to ram the cow, or you can use the following command to make it ram the cow:

/execute as @e[type=minecraft:goat,limit=1,sort=nearest] run data modify entity @s Brain.memories."minecraft:ram_cooldown_ticks".value set value 1

→  Notice how goats will attempt to ram entities that are outside of the world border.