PhantomCamera3D.set_third_person_rotation() rotates the camera around its own

[marinho]

Issue description

For a PCam with follow_mode as ThirdPerson, I wrote this code expecting the camera to rotate around the target (which is the character object), but instead, this method is actually rotating the camera around its own Y.

const SPEED = 5

func _input(event):
	if event is InputEventMouseMotion:
		var x = event.relative.x * 0.001 * SPEED
		var old_rotation = %PCamThirdPerson.get_third_person_rotation()
		var new_rotation = Vector3(
			old_rotation.x,
			old_rotation.y + x,
			old_rotation.z
		)
		%PCamThirdPerson.set_third_person_rotation(new_rotation)

Steps to reproduce

1. Add a CharacterBody3D, Camera3D, PCamHost and PCam to the scene, plus some ground with respective collisions
2. Set PCam with:
   a. Priority = 0
   b. Follow Mode = Third Person
   c. Follow Target = CharacterBody3D
   d. Follow Offset = (0, 10, 10)
   e. Spring Length = 10
   f. Create a script and add the code I wrote above
   g. Run

(Optional) Minimal reproduction project

Additionally, if I set Look at Mode to Siple and Look at Target to CharacterBody3D (in face any other object), the camera will as well point to bottom with no clear reason.

Thanks!