Reproduction steps:
1. Open user's attached project in "TestUnityWebRequest.zip" (for AppleTV check Notes)
2. Build the project for iOS
3. Run and Deploy the project in Xcode to an iOS device
4. Press "1. SendUnityWebRequest" button
5. Wait for indication in the Log (in the Application itself) that the request is complete
6. Press "2. Application.Quit()" button

Expected result: Application quits instantly
Actual result: Application freezes and hangs for 30-60 seconds before quitting

Reproducible with: 2019.3.10f1, 2020.2.0a5
Could not test with: 2017.4, 2018.4 because of errors in the console (related to built-in packages, however restoring to defaults was not available)

Devices tested:
Reproducible with:
VLNQA00310 iPad Pro 12.9 (iOS 11.2.1)
AppleTV (tvOS 13.3.1)
Not reproducible with:
VLNQA00285, Samsung Galaxy J4 Core (SM-J410F), Android 8.1.0, CPU: Snapdragon 425 MSM8917, GPU: Adreno (TM) 308

Note: to test on AppleTV open tvOSAuto.zip, open Samplescene, do steps 2, 3 for tvOS and the rest of the steps will be automatically via Script. Inspect the freeze.