How to reproduce:
1. Make sure HDR is enabled within the operating system and an HDR-compatible monitor is used
2. Open the “HDR_UI_Bug” project
3. Open the “SampleScene”
4. Make sure “Allow HDR Display Output” is enabled (Edit > Project Settings > Player > Other Settings)
5. Observe the Game view
6. Build And Run then observe the Player

Expected result: the “UI” GameObject is visible
Actual result: the “UI” GameObject disappears

Reproduced with: 2022.2.21f1, 2023.1.0b18, 2023.2.0a16
Could not test with: 2020.3.48f1 (UI Document functionality missing, HDR settings missing), 2021.3.26f1 (Different HDR settings)

Reproduced on: Windows 10 (by reporter), Windows 11

Notes:
1. On Windows 11 enable HDR by going to Settings > System > Display > “Use HDR”
2. In 2021.3.26f1, the expected result is partially achieved, but the color range is oversaturated