The vertical rotation of the player's head is fully synced with the mouse cursor, unlike the horizontal rotation

This issue is related to MC-261026, which is working as intended. Currently, only the horizontal rotation of the player's head experiences a delay, while the vertical rotation remains fully synced. This inconsistency means that when turning up or down in third person, you never see the top of your head unless you move diagonally, whereas you can easily see the side of your head when turning horizontally.

Steps to reproduce

1. Go into third person
2. Turn the camera horizontally
3. Turn the camera vertically, ensuring that you do not move it horizontally at the same time

Observed Result: You do not see the top of your head because your vertical rotation is not delayed, unlike the horizontal rotation.
Expected Result: You should be able to see the top of your head, with the vertical rotation also experiencing a delay.