How can unread notifications be identified in the security center?

In a security center, unread notifications are typically identified by a blue circle icon. This choice is aligned with common design practices in user interfaces, where a blue circle often indicates new or unread items that require user attention. This visual cue helps users quickly distinguish between items they have already reviewed and those that still need to be addressed, enhancing the overall usability of the security center.

The other icons, such as a green checkmark, usually represent completed tasks or indicators of success, which do not signify unread notifications. A red triangle is often used for critical warnings, and a yellow exclamation mark typically indicates caution or attention needed, but neither of these specifically points to unread items. Therefore, the blue circle serves the specific purpose of marking unread notifications effectively.