Undocked windows disappear or flicker intensely when Picking Element with UITK Debugger

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Open any window and undock it
3. Click the burger icon in the undocked window and select UI Toolkit Debugger
4. Click the Pick Element button in the UI Toolkit Debugger window
5. Move the mouse around the Editor or move the mouse towards the undocked window
6. Observe the Editor

Actual results: All the undocked windows disappear or flicker including the UI Toolkit Debugger window, but the Pick Element functionality remains active

Expected results: All the undocked windows are still showing

Reproducible with versions: 6000.3.0a3

Not reproducible with versions: 6000.0.54f1, 6000.1.14f1, 6000.2.0b12, 6000.3.0a2

Tested on (OS): macOS Silicon Sequoia 15.5

Notes:

• Does not reproduce on Ubuntu 24.04
• Some windows disappear, some windows in some conditions start flickering instead of disappearing