How to reproduce it:
1. Open the user's attached project "RenderFrameIntervalTest.zip"
2. Build and Run the project on the Android device
3. Disconnect USB from the device
4. Observe the white square and notice that the Delta Time value changes
5. Send the app to the background and wait 1 - 2 minutes
6. Resume app
7. Observe the white square and Delta Time value

Expected result: Delta Time's value frequently changes
Actual result: Delta Time's value is constant 0.3(3)

Reproducible with: 2021.1.0a5, 2021.1.7f1, 2021.2.0a17
Not reproducible with: 2018.4.35f1, 2019.4.26f1, 2020.3.8f1, 2021.1.0a4

Reproduced on these devices:
VLNQA00122, Samsung Galaxy S9 (SM-G960F), Android 10, CPU: NOT FOUND, GPU: Mali-G72
VLNQA00331, Huawei P20 lite (ANE-LX1), Android 9, CPU: HiSilicon Kirin 659, GPU: Mali-T830
VLNQA00321, Xiaomi MI 9 (MI 9), Android 10, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00038, Htc Desire 510 (HTC Desire 510), Android 4.4.3, CPU: Snapdragon 410 MSM8916, GPU: Adreno (TM) 306
VLNQA00285, Samsung Galaxy J4 Core (SM-J410F), Android 8.1.0, CPU: Snapdragon 425 MSM8917, GPU: Adreno (TM) 308

Notes:
- Reproducible when the device is disconnected from PC