Object count skyrockets using TileMap runtime updates.

[DuneTruffle]

Tested versions

produced in v4.2.1.stable.mono.official [b09f793]

System information

windows 11 - v4.2.1.stable.mono.official [b09f793]

Issue description

object count and memory consumption sky rockets when hiding and showing the tilemap after the scene is run

Steps to reproduce

1. open project
2. run scene
3. hide and show the Tilemap in the editor while the scene is running
4. observe object count skyrocketing

Minimal reproduction project (MRP)

minimum reproduce.zip

[lavish123409]

I am trying to reproduce the issue on my machine.

I do not know where to see the object count in it. Like the object inside tilemap is constant (i.e., Settlement Camera) in the Remote area, so I am confused where to look for it.

[Zireael07]

The object count is in the debugger tab

[kleonc]

@DuneTruffle From the bug_report template:

• Note for C# users: If your issue is not C#-specific, please upload a minimal reproduction project written in GDScript. This will make it easier for contributors to reproduce the issue locally as not everyone has a .NET setup available.

Here's a simplified GDScript version of the script from the MRP:

extends TileMap

func _ready() -> void:
	var mapDimensions: int = 16
	for y in mapDimensions:
		for x in mapDimensions:
			set_cell(0, Vector2i(x, y), 0, Vector2i(0, 0))

func _use_tile_data_runtime_update(layer, coords):
	return true

func _tile_data_runtime_update(layer, coords, tile_data):
	pass

The issue still happens:

So using C# is unrelated in this case.

Same in a release-export:

func _process(delta):
	%Label.text = "%d" % [Performance.get_monitor(Performance.OBJECT_COUNT)]

func _on_button_pressed():
	visible = !visible

So not an editor issue.

Can reproduce since v4.2.dev5.official [e3e2528] (doesn't happen in 4.0.x, 4.1.x).
So likely a regression from #81070. cc @groud