Duplicated PanelRenderer GameObject is inserted at the top of the Hierarchy instead of below its source when duplicating a 3rd time

Steps to reproduce:

1. Create a new project
2. Go to Edit > Project Settings > UI Toolkit
3. Enable the "Enable in-scene UI Authoring" property
4. In the Hierarchy, right-click > UI Toolkit > Panel Renderer
5. Select the created Panel Renderer and press CTRL+S/CMD+S to copy
6. Press CTRL+V/CMD+V three times
7. Observe the placement of the third duplicated Panel Renderer

Actual results: The 3rd duplicate (and each one after) is inserted between "Main Camera" and "Directional Light"

Expected results: All duplicates should be inserted directly below

Reproducible with versions: 6000.6.0b5, 6000.7.0a3

Can’t test with versions: 6000.3.20f1, 6000.5.5f1 (no "Enable in-scene UI Authoring" property)

Tested on (OS): macOS 26.5

Notes:

• Only reproduces with UI Authoring enabled
• Each subsequent duplicate after the 4th also lands in the same wrong position (between Main Camera and Directional Light), not progressively further down or back at the bottom
• Saving the scene moves the misplaced duplicate(s) back to the correct position at the bottom of the Hierarchy