How to reproduce:
# Open the project "IN-64200_HDRP Multi-Camera UI HDR Tests"
# Open “Test A“ scene
# Drag the Game window to a -10-bit- HDR-capable display and maximize it
# Enter Play mode
# Press 'H' to manually toggle HDR ON
# Observe that the Game window

Expected result: When pressing ‘H', the Game window changes
Actual result: When pressing 'H', the Game window doesn’t change

Reproducible with: 2022.1.0a16, 2022.3.17f1, 2023.2.6f1, 2023.3.0b2
Not reproducible with: 2021.3.34f1, 2022.1.0a15

Reproducible on: Windows 11 Pro (23H2), Macbook Pro 2018, Mac Mini M1

Note: In 2022.3.15f1 HDR doesn’t initially turn off, but after pressing ‘H' to turn HDR on and off, HDR turns off.
Note: When repro-ed on Mac, HDR doesn't turn off at all given any number of button presses. With/without 10-bit monitor. Windows not tested for this specific behavior.