Domino 8.5 and Compact

After upgrading 2 production servers to Domino 8.5 yesterday, I found this entry on the console when running a compact -c on the users mail mailfiles.


I have seen this on several databases, but the amount of KB (  ~ + 11MB ) surprised me. Can someone explain this behaviour, pls?

All databases had ODS48 format with LZ1 compression and design and document compression enabled.