Applying a levitation effect to a mob that is currently executing a look_at_player or random_look_around behavior can cause it to snap to a previous rotation. I'd expect it to keep its current rotation.

On the attached video you can see that the second sheep I spawned rotated towards me, but once I run the effect command, it snaps back to a cardinal direction.

This is hard to test and show, but it is an inconvenience for content creators.

Speculation:
It's almost as if there was a client side rotation that is separate from the mob's actual rotation, and the levitation effect causes the client side one to sync with the server. This might also be apparent when using local coordinates (^ ^ ^) on a mob that is rotating client-side.