Steps to reproduce:

1. Create a new Unity Project
2. Create a UI Document (Assets > Create > UI Toolkit > UI Document)
3. In the newly created PanelSettings, set Render Mode to World Space
4. In the Project window, create a new UXML (Right-click > Create > UI Toolkit > UI Document)
5. Double-click the UXML to open it in the UI Builder
6. Add two buttons to the canvas
7. In the Hierarchy, select the UI Document and in the Inspector, set Size Mode to Dynamic
8. Observe the UI size in the Scene View
9. In the Project window, select the PanelSettings asset
10. Change the Render Mode from World Space to Screen Space - Overlay
11. Observe the UI size again in the Scene View

Actual results: The UI size changes noticeably when switching the PanelSettings Render Mode

Expected results: The size of the UI should remain consistent regardless of the Render Mode

Reproducible with versions: 6000.2.0b1

Tested on (OS): macOS 15.5 (Silicon M4), Windows 11

Notes:

•  The inconsistency might affect layout fidelity during UI transitions or when toggling modes dynamically at runtime.