Entities' eye levels aren't adjusted when their models are flipped upside down

The Bug:

Entities' eye levels aren't adjusted when their models are flipped upside down.

For context, an entity's model can be flipped upside down by naming the entity "Grumm" or "Dinnerbone".

Steps to Reproduce:

1. Summon a creeper that's upside down by using the command provided below.

   /summon minecraft:creeper ~ ~ ~ {NoAI:1b,CustomName:'"Dinnerbone"'}

2. Enable entity hitboxes by pressing F3 + B.
3. Observe the eye level of the creeper and see if it matches its model.

Observed Behavior:

Entities' eye levels aren't adjusted.

Expected Behavior:

Entities' eye levels would be adjusted.