The 2.4 workspace identifiers were free text and same did not survive the migration. Each one is replaced with a short name. Mapping was applied one time only, old identifiers will not resolve in 2.8.
2.4 was writing reports as {report_type}_{workspace}_{DDMMYYYY}. 2.8 writes {workspace}/{report_type}-{YYYYMMDD}. Any script which is parsing old format needs to be updated accordingly.
Nightly collection writes into /opt/assetmapr-backup/archive/{workspace}/ on backup host. This path is same as 2.4 and continues to be the location for anything retained beyond 90 day window.
Whatever could not be migrated we moved to the old data folder instead of deleting. It is not reachable from 2.8 anywhere. Legacy platform overview has the details of what went there and under what naming.