Malwarebytes does not find these

[Michael1941]

My MacBook Air gets hammered with these apparent System Warnings. They shoot on to the screen, top right. Of course, I don't open them. But Malwarebytes does not find the source. Can you help me? I have not been able to tie them down to a browser, or any other application. Thanks - in anticipation.

[treed]

These are not caused by malware on your machine. You have been tricked into allowing notifications via your web browser from a malicious website.

Depending on what browser you're using, the means for examining the notification settings varies. In Safari, choose Settings from the Safari menu. Then click the Websites icon in the toolbar along the top of the Settings window. In the pane that opens, click Notifications in the left-hand list. Finally, look for a website shown with the macOS System Settings icon (as shown in your screenshot) and change it from Allow to Deny. This will prevent that site from ever showing you notifications again, or asking you to allow it to show you notifications.

I'd also recommend unchecking the box labeled "Allow websites to ask for permission to send notifications." This will prevent this kind of thing from happening again in the future.

[Michael1941]

Thank you SOOOO much. This did the trick!!!