Reproduction steps:
1. Open the project in "ondemandrenderingbug.zip"
2. Build "SampleScene" for iOS and deploy it to a device
3. Shut down the application and disconnect the phone
4. Open the application with the phone disconnected
5. Take note of UnscaledDeltaTime and lock the screen
6. Wait for a minute and unlock the screen
7. Inspect the game

Expected result: UnscaledDeltaTime will be the same as before locking the screen
Actual result: UnscaledDeltaTime will be increased and the application will run like it is sped up at 5 FPS

Reproducible with: 10.4.0 (2020.3.1f1), 11.0.0 (2021.1.0f1), 12.0.0 (2021.2.0a10)
Could not test with 2018.4.33f1, 2019.4.23f1 because of errors in the console after the downgrade

Devices tested:
Reproducible with:
iPad Pro 12.9 1st gen (iOS 13.4.1)
iPhone 12 (iOS 14.1)
Not reproducible with:
N/A, Samsung Galaxy S9 (SM-G960F), Android 8.0.0, CPU: Exynos 9 Series 9810, GPU: Mali-G72
VLNQA00318, Oneplus 7Pro (GM1913), Android 10, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00231, Huawei HUAWEI Mate 20 Pro (LYA-L29), Android 9, CPU: HiSilicon Kirin 980, GPU: Mali-G76
VLNQA00339, Lge LG V50 ThinQ 5G (LM-V500N), Android 10, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00316, Samsung Galaxy Note10 (SM-N970F), Android 9, CPU: Exynos 9 Series 9825, GPU: Mali-G76

Notes:
1. The issue will not reproduce if the phone is connected to a Mac via USB (this means that you will not be able to debug using Xcode)
2. Videos attached in edits below