Have seen an increase of this on client machines. Check that you don't have malicious websites in your browser's notification settings. I usually delete the allowed websites and turn off notifications unless the client wants them. Also check your browser extensions.
I have a windows 11 Dell desktop and a windows 11 Acer laptop.  Every hour or so a pop up window appears at the down-right corner of the screen saying that the computer is infected with viruses and I need to buy McAfee antivirus program to clean it. Some other times it says “Trojan virus detected turn on your antivirus via Microsoft Ede.” The message is under the title “a.captcha4you.top”. I've done a google search to find that “captcha4you.top” is an adware or malware which somehow was installed in my computer. McAfee is not installed on my computer. F-Secure in installed instead. I've tried a few things to get rid of this virus but to no avail. I have reset my web browser settings. I've tried to clean it with Malwarebytes, HitmanPro, ESE Online Scanner. Nothing has worked so far. Has anybody had a similar experience? 
Virus removal