You noticed that the Outlook Server Side Integration is synchronizing cancelled tasks, even very old ones, to SAP Cloud For Customer where they are displayed as In Progress.
SAP Cloud For Customer
This is how the current filter logic works for the synchronization of Tasks.
Server Side synchronization syncs completed tasks within 2 weeks time frame and all other tasks without any time filter.
Groupware; Server Side; Tasks; Status; , KBA , LOD-CRM-GW-SCC , Invisible CRM - Smart Cloud Connect Solution , Problem