No Server Response when using Proxy

Originally opened by @FuckingToasters on 2022-09-05 13:23:01 in encode/httpx

Describe the bug
Earlier, i had a read timeout error when using proxies which i solved by adding timeout=None in the httpx.Client() function.
Now, when choosing http proxies it work fine for some time but it randomly start crashing with a exception: Server closed without sending response
Don't tell me stuff like "that's a duplicate of ..." I've looked on other Answers on Stackoverflow & Github but none of these helped me to solve the issue i am facing.

To Reproduce
Do a http request to discord.com while using proxies:

    data1 = {"foo": "bar"}
    with httpx.Client(headers=HEADERS, timeout=timeout, proxies=proxyauth if proxytype != "" else None) as client:
        resp2 = client.post("https://discord.com/api/v9/users/`@me`", json=data1)
    lock.acquire()
    if resp2.status_code == 204: pystyle.Write.Print("\t[+] Successfully requested api!\n", pystyle.Colors.green, interval=0)
    lock.release()

Expected behavior
In case you use a proxy, it should request the api as usual without the traceback.

Start by reproducing the Discord request through an HTTP proxy using the shown httpx.Client configuration, recording the Python, httpx, proxy, and traceback details. Trace the request from the Client entry point to the proxy response handling; done means the request completes without the reported server-closed exception under the reproduced conditions.