For one of our projects, we see that there are 117 defects outstanding which means (Not Equal to Closed / Rejected / Verified). When we go to Defects Trend in Dashboard, we see 120 in the graph which is more than the filter on the Defects Page.
Release : SAAS
Component : AGILE CENTRAL
This can occur if defects were deleted from the project without being closed OR if defects were permanently deleted (purged) from the project without being closed.
For more detail about how the Defects are calculated please see this article: Defect Trend Application is not returning accurate results
See the document on how to search the Recycle Bin for artifacts in a specific project