Deleted computer still appears in custom reports

In these custom reports a computer appears that does not exist for more than a year. This computer has been removed from active directory and does not appear in the Inventory view or in the All systems view of Patch Mgmt or in the SoM view. Neither it appears in pre-built reports like the "All computers" report.
But in existing custom reports and also when I create a new custom report - type 'computer' or 'software' does not matter - this computer still appears.
This is a problem for us because I cannot rely on the result of custom reports.

What is causing this issue and what is the solution?