Annoying spam pop-ups in Safari 18.5

Are these Notifications that are appearing on the upper right of your screen?

If so, that is due to a website that you have allowed to send you those Notification. All you need to do is go to Safari > Settings > Websites > Notifications, and remove all the sites you see there. That will solve the problem.

Lt. Kije wrote:

Thanks for the quick and helpful reply. Yes - those have been appearing in the upper right corner. I followed your instructions, but there weren't any websites found there, only a small globe icon. So I deleted that! I'll keep you updated and thanks again.

Yep, I believe you got it. The website did not include their name in hopes you would not see it. Fortunately, the default globe icon will appear as a placeholder even if one is not provided.

Stop unwanted Notifications - Apple Community

You’ll also want to check the box to prevent future prompts for sending you notifications, available on the same website notification configuration.