ProxyMgr registry key keep using the old setting

Question

I am using GPO to control the AutoconfigURL for using proxy.pac file, somehow; I found that my proxy.pac URL was keep using the old setting which was 3 months ago, actually; I have updated the new registry key for the new AutoconfigURL in Default Domain Policy.

When I looked at my computer Registry, I found that a key like this keep pointing to the old URL, eventhough I delete it from ProxyMgr key, it will come back somehow.

For this "{8F20F6B0-E20F-40CD-A58B-B2E2B3A9A67B}", where does it come from? Can you find the root file of this for further investigation?

Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\iphlpsvc\Parameters\ProxyMgr{8F20F6B0-E20F-40CD-A58B-B2E2B3A9A67B}

Also, if Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings is the only key to manage the AutoconfigURL for users?