isPostback_RC_Pendingupdates

Windows Key+R > Type services.msc and press Enter > Locate Background Intelligence transfer and ensure it is set to Start and Automatic. Also do the same for Windows Update service as well

If they are already set to start, stop them, start and Automatic and restart your computer.

I noticed this too and I *think* (?) it may be a virus.

Check your AppData folder, in %userprofile%\AppData\Local\Microsoft\Windows\Safety\edge\remote, and also under blahblahblah\Windows\shell\remote, I have some files with names like e.g. script_336273089957297446437176090113554533354.rel.v2 which, if you open them in notepad, contain a bunch of minified javascript.

It doesn't get any hits on VirusTotal or Hybrid-analysis, so whatever it is definitely goes undetected, but I think it might be intentionally manipulating the Defender antivirus settings/logs to obscure whatever it's doing.

A lot of weird processes like rundll32.exe and WUDFHost.exe are always running, I think it might be transmitting some data to somewhere?

Do you (or anyone else in this thread) have any of those types of files in your AppData? if so, and if this isn't just a regular Defender thing that I'm worrying about unnecessarily, then maybe we should look into it. However that javascript looks extremely weird and I can't imagine it's just some normal built-in Windows thing. Looks to me like some zero-day exploit or something that I might've installed with a compromised app somewhere. I did notice all the activity I'm noting started happening after I set up this windows build fresh (it's the latest Insider build, 19613_1005) and ran my Chocolatey install script which installs a bunch of my usual apps.

I have the same type of file too! I wonder if it really s a virus

Windows Key+R > Type services.msc and press Enter > Locate Background Intelligence transfer and ensure it is set to Start and Automatic. Also do the same for Windows Update service as well

If they are already set to start, stop them, start and Automatic and restart your computer.

I have the same "Issue" as KerrieLewis.  BITS is/was set to "delayed start" so it is running, but not immediately when the system first boots.  IMHO this should not cause any problems but the system in question is not updating itself to 1903, and all my other computers have already done the update.