Object ID and instance ID of custom class

Godot Version

4.3

Question

When running program,
in Remote tab,
the object ID and instance ID of label_04 is the same.
the object ID and instance ID of v3 is not the same. why?

And why is the instance ID of v3 negative?

extends Node2D
@onready var label_03: Label = $Label03
@onready var label_04: Label = $Label04

var v3 : my_item = my_item.new()

class my_item:
	var amount : int    = 1
	var name   : String = "AAAA"
	
func _ready() -> void:
	label_03.text = "%s" % v3.get_instance_id()
	label_04.text = "%s" % label_04.get_instance_id()