How do I remove a persistent fake-virus alert popup?
I've got a Surface Go 4 running Windows 11 in my family where today the user clicked "allow" on a popup message she got asking about cookies or something while browsing in Edge. Since then, the PC gets a popup in the lower right corner. She got maybe 15 different versions of the popup. It stays on-screen for 10 to 30 seconds, then goes away without clicking on anything. The next will pop up in 5 seconds to 5 or more minutes. Headings include "(McAfee logo) Virus Alert", "(Windows logo) Sytem Damaged!", "(microsoft logo) "Microsoft Windows Defender TROJAN found in /Win32!", "(shield image) Virus & threats protection - Threats found (16)."
All have some spelling or syntax errors but otherwise look convincing.
All have the same link snippet: "crot50ohubcc738pnb00.loopdeviceconne..."
We haven't clicked anywhere on or near the popup when it's on screen.
Steps I've tried:
Windows defender checked status: has been running ok, last updated last night (9/2224) around 10:20pm.
Powered off, shut off network, powered on, Windows defender quick scan: came up clean. No pop-ups while network was off.
Windows defender offline scan: behaved normally (warned of reboot, reboot, scan) came up clean. Pop-ups resumed when network was turned on.
Taskmgr doesn't show anything I recognize as bad in startup apps list or in running processes, but I'm not current enough to know what processes might be bad.
Example alert pic shown below:
