Bug UnityWebRequest connection reuse broken

Seems like after Unity 2020.3.9 update connection reuse on Android is broken. I made simple test project with one button making http request.

Code (csharp):

1. private IEnumerator ReqRoutine(string url)
2.     {
3.         var req = new UnityWebRequest(url);
4.         var op = req.SendWebRequest();      
5.         yield return op;
6.         _txt.text = op.webRequest.responseCode.ToString();
7.         req.Dispose();
8.     }

I built it wih Unity 2020.3.8 and, as expected, fiddler showed that when I made a series of requests (10 in a row) they all used the same connection. After that I tried several builds with different Unity versions (including 2021.2.5f) and all of them showed the same behaviour: every request starts new connection. So, I have one active connection in version 2020.3.8, but starting with 2020.3.9 I have 5 active connections (size of connection pool?) and no connection reuse.

Is this an expected behaviour or not? Is there a way to make UnityWebRequest reuse connections on Android? Or maybe I'm doing something wrong? ))

 

I second that, keep-alive is badly broken since 2020.3.9.