Possible reasons:

a. New objects are still being replicated to the destination cluster. This could just be because:

    * a large number of objects have recently been written

    * the communication pipe is too small for the amount of data being written

    * the replication task is paused (check admin)

    * replication task is set to run in a time window (check admin tool)

b. Small differences can come from the MatrixStore system files - small files that are used for admin purposes and which aren’t replicated

c. Someone has directly deleted a number of objects at the destination cluster

d. The source cluster could have a number of deleted files in its trash can