The spear in an entity's main hand gets animated when their off hand arm is swung using /swing

The recently added /swing command enables the swinging animation of entities' arms (mainhand or offhand). When an entity who’s wielding a spear on their main hand gets their offhand swung using the /swing command, the spear on their main hand gets animated alongside their offhand arm.

How to reproduce:

1. Summon an entity (such as a zombie or a skeleton or their variants) wielding any type of spear in their main hand. Example command: /summon minecraft:wither_skeleton ~ ~ ~ {equipment:{mainhand:{id:"minecraft:stone_spear"}}}

2. Swing their offhand using the /swing <targets> offhand command. The quickest way to achieve this is by looking at the summoned entity so that you can see their UUID in the targets autocomplete.

Expected result:

Their offhand arm should get swung without the spear getting animated.

Observed result:

Their spear gets animated along with their offhand arm swinging.