As of core v14.2.0 progress is reported for both directions at the same time

This means that object-store api gets this notification for registered upload callbacks, for example, on DOWNLOAD message with changesets even if there is no real progress on uploading outstanding local changesets. In practise, this means that there are sequences of duplicated values for (transferred/transferable) reported through object-store api for every direction separately.

Callback call should only be called when the real progress has been made on either download or upload, and it should be invoked separately to match object-store side.