McAfee

Popups that appear at the upper right of your Mac's screen are Notifications. Does that describe what you are encountering?

Stop annoying Notifications by reviewing Customize website notifications in Safari on Mac - Apple Support. Apparently, you granted one or more websites the authority to harass you with annoying Notifications. When confronted with an offer to do that, your automatic, reflexive reply ought to be "just say no."

Excerpted from Effective defenses against malware and other threats - Apple Community:

Beware spontaneously appearing, unsolicited popups demanding immediate action. Think before you click.

• ...
• If you encounter a website, popup, text message, email, or phone call alleging your Mac is infested with some ick or that you need to take immediate action lest dire circumstances ensue, it is 100% fraudulent. Ignore it. Read Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams.
• The same goes for website Notifications — attention-getting banners that appear at the top right corner of your screen. Safari gives you a great degree of control over them: Customize website notifications in Safari on Mac. Most of those Notifications are simply annoying, but some are intended to frighten and deceive you into installing something nefarious.

Research Customize website notifications in Safari on Mac - Apple Support. For example, use Safari's Preferences or Settings menu > Websites. Under General, you will find Notifications. Websites that have asked for permission to show you Notifications will be listed there. You can (and probably should) select every one of them and click Remove. De-select the box that allows websites to send Notifications and you will no longer even be asked.

Consider doing the same for Pop-up Windows. As Effective defenses against malware and other threats - Apple Community explains,

• Popup windows are useful and required for some websites, but unsolicited popups are commonly used to deceive people into installing unwanted software they would never intentionally install.

If you still have questions after reviewing the above, please write back. There is an icon in your screenshot that may indicate the presence of an ill-conceived "anti-virus" app on your Mac, but I cannot be certain. Those things are all scams.