Entities rotating their heads while idle is client side only

The bug

When an entity randomly rotates, while standing on the same position, the server does not update the entity's rotation, causing the Rotation NBT and local coordinates to be inaccurate to what players see.

How to reproduce

1. Summon a zombie
2. Run this command in a repeating command block:

   /execute at @e[type=zombie] anchored eyes run particle flame ^ ^ ^4 0 0 0 0 1
   

   → When the zombie randomly looks around without moving, the particle will stay in the same place, rather than move with the zombie's looking direction

Code analysis

Potential code analysis by Chumbanotz can be found in this comment.