create a .bat file with these lines as its content:
@echo off
set HTTP_PROXY=
set HTTPS_PROXY=
setx UNITY_NOPROXY localhost,127.0.0.1
start "" "C:\Program Files\Unity Hub\Unity Hub.exe"

MAKE SURE THE PATH POINTS TO WHERE UNITY HUB IS ON YOUR OWN MACHINE
Run the file by double clicking or via PowerShell. May or may not need to run as Administrator

Upvote if this has helped you so that more people see it!!

see my forum post here for additional help:
https://forum.unity.com/threads/using-proxy-will-cause-unity-hub-failed-to-open.1187914/#post-7810242