Steps to reproduce:
1. Open the attached "bug-stopcoroutine-2022.3.zip" project
2. Open the "Assets/Scenes/SampleScene" scene
3. Enter the Play Mode
4. Observe the Console

Expected results: StopCoroutine() only stops the specified coroutine and does not affect nested coroutines
Actual results: StopCoroutine() stops nested coroutines

Reproducible with: 2021.3.35f1, 2022.3.20f1, 2023.2.11f1, 2023.3.0b8

Reproducible on: Windows 11 Pro, MacOS 13.6.4 (user's)
Not reproducible on: No other environments tested

Notes:
- Calling StopCoroutine() immediately after StartCoroutine() is synthetic and only used to surface the problem
- Expected log:
UnityWebRequestTest.Start()
ImageAssetBundleLoader.StartLoad()
AssetBundleManager.LoadAssetBundle started...
AssetBundleManager.DownloadOrLoadFromCacheBundle started...
RestHandler.SendWorker started...
AssetBundleRestWorker.Send started...
AssetBundleRestWorker.Send completed!
RestHandler.SendWorker completed!
AssetBundleManager.DownloadOrLoadFromCacheBundle completed!
- Actual log:
UnityWebRequestTest.Start()
ImageAssetBundleLoader.StartLoad()
AssetBundleManager.LoadAssetBundle started...
AssetBundleManager.DownloadOrLoadFromCacheBundle started...
RestHandler.SendWorker started...
AssetBundleRestWorker.Send started...
- The issue can be circumvented using "WORKAROUND_1" in "AssetBundleManager.cs" or "WORKAROUND_2" in "AssetBundleRestWorker.cs"
- The issue does not occur in the 2019.4 stream according to the user