The little symbol in the right-hand corner of the shift always has a meaning. Whether it means that the shift is still in draft mode (unpublished) or that the shift has been seen by the employee (seen), you can refer to it to find out more about its status.
Here are the different options.
You can also consult this detailed article in order to find if your "Employee has seen his schedule"
You can also find out more about the differentiation of auto-assign shifts in the article "Auto-Assign"
Click on this article for more information on " How to recognize published and unpublished shifts "