The Nvidia process appears legitmate. I found a number of links describing what the process is and what it does. You can easily go to Nvidia's website or other sites as well to learn more.
What is more interesting are those enabled Startup Apps.
For example "Hotkey for Dev Diagnostics": that is the sort of startup app that I would consider as a potential culprit. Especially if you do not knowingly use the app. [It does not appear on my computer.]
The startup app may have some purpose. Hopefully an app that you recognize and use.
Fair enough but it could also be buggy or corrupt.
What to do - simply disable the app from Startup. Make no other changes and keep track of any settings that may be involved.
Determine 1) Does the pop-up window stop appearing, and 2) does anything else go wrong or stop happening?
If that does not work then disable some other startup app that you do not need or recognize. Go online and look for more information just in case the startup app is part of something else you run.
Even if the startup app is necessary - again it could be buggy or corrupt.
Working through the list will take some time and effort. You must be slow and methodical.
Ideally you will discover some startup app that when Enabled = Pop-up Window and Disabled = No Pop-up Window".
As always, ensure that all important system data is backed up at least 2 x to locations away from the computer in question. Verify that the backups are recoverable and readable.
= = = =
Try running the Get-Process cmdlet again.
Open Powershell as Admin and type "Get-Process" (without quotes) at the PS> prompt.
There should be a long list of processes presented. The only part that is immediately meaningful is the ProcessName column. Look for names in the ProccessName Column may include or imply "npm". "reg", etc..
Indeed the process may be being launched/enabled and immediately disabled. There could still be other processes involved. Just look.