Unusual Website Popups Without Interaction

I have already created a post for Chrome on the Google Support forums. However, in case they cannot provide adequate advice for a system-level issue, I also posted on the Microsoft forums, and now I am asking here as well (this is copied from my Microsoft post).

Odd new tabs are opening in Google Chrome, even when the app is closed (or in "sleep" mode). These are typical scam-like and untrustworthy "antivirus" and "dangerous malware" alert tabs, but they all originate from completely different web addresses (or at least display different domain names).

Are there deeper strategies beyond basic malware scans—such as inspecting system files or capturing event logs and timestamps—that could help me track down the source of these popups?

I have already tried various basic troubleshooting methods without success, including running several Microsoft Security scans and checking system files. The most recent website domain was "defendervault.shop" (I omitted the rest of the URL for privacy). I do not recall downloading anything clearly risky, though I might have missed something.

Any assistance or guidance you can offer to help track down and resolve this issue would be greatly appreciated.

Your thread post hard to read anyway scan your computer for Adware, short for advertising-supported software, is a program that automatically generates and displays online advertisements on your device.

Run a full system scan using reputable cybersecurity programs such as Malwarebytes to detect and safely quarantine unwanted applications.

Also scan your computer with adwcleaner.

I don't know which applications you have checked your system with, but I would do a full system scan with Superantispyware (no need to register, the trial version works fine) and remove all results. If the results (including cookies) are more than 400, I would do a second full system scan with Malwarebytes Antimalware to find any leftovers. Then I would do a full system scan with Windows Defender or whatever antivirus you are using. I would configure it not to ignore small files and to also scan inside archives. If the issue persists, rather unlikely, I would consider to backup all my data, wipe the disk and reinstall Windows.

In Chrome Settings - Notifications, are any sites allowed to show notifications? If so, remove or block them. Also, disable Chrome running background apps when closed. That is also in Settings.