Skeleton3D with bones causes continuous editor update

[stoofin]

Tested versions

Does not occur in 4.2
Does not occur in 4.2.2
Does occur in 4.3beta1

System information

Godot v4.3.beta1 - Ubuntu 24.04 LTS 24.04 - Wayland - Vulkan (Forward+) - dedicated AMD Radeon RX 6600 (RADV NAVI23) () - Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (8 Threads)

Issue description

The editor redraws constantly when a Skeleton3D with at least 1 bone is present
(Editor Settings/Interface/Editor/Update Continuously is unchecked)

Steps to reproduce

Open a rigged model or add one to the open scene. Enable the Update Spinner and watch it spin.

Minimal reproduction project (MRP)

This scene triggers it:

[gd_scene format=3 uid="uid://brl1aoxyriojm"]

[node name="rigged-cube" type="Node3D"]

[node name="Skeleton3D" type="Skeleton3D" parent="."]
bones/0/name = "Bone"
bones/0/parent = -1
bones/0/rest = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0)
bones/0/enabled = true
bones/0/position = Vector3(0, 0, 0)
bones/0/rotation = Quaternion(0, 0, 0, 1)
bones/0/scale = Vector3(1, 1, 1)

editor-spinning-min.zip

[matheusmdx]

Bisecting points to #87888 as the culprit:

[TokageItLab]

This depends on the existence of the internal PhysicalBoneSimulator and should not occur if the compatibility mode is disabled. In the case of the update flag relying on SkeletonModifier, we may be able to consider if it can be skipped if it is not active.