How to reproduce:
1. Open the attached “MTSM_UIDocOrder.zip“ project
2. Open the “BootScene“ Scene
3. Enter Play Mode
4. Press the Enter (click on “Start“)
5. In the new window, press the Escape button
6. Observe the Game window. Notice that the pop-up is displayed before the other remaining UI
7. Build and run the project
8. Repeat steps 3 and 4
9. Observe the Player

Actual result: The pop-up is layered behind the other UI, unlike in the Editor
Expected result: The pop-up is layered in front of the other UI, like in the Editor

Reproducible with: 2023.1.0a26, 6000.0.62f1, 6000.2.14f1, 6000.3.0f1, 6000.4.0a5, 6000.5.0a2
Could not test with: 2023.1.0a1 (Unable to solve compilation errors)

Reproducible on: macOS 15.3.2 (24D81) (M1 Max), Windows 11 Pro (24H2)
Not reproducible on: No other environments tested

Notes:
- Reproducible only in the Player
- Unable to reproduce the issue on a new project
- Increasing the Sorting Order property does not fix the issue