This release updates the various bookmark/book queries so that store-purchased Kobo titles are ignored.
For most users, they'll want to use the officially supported Readwise integration to make use of remote syncing and what not.
October is intended to just cover the sideloading part of the equation but until now, there was never any special handling of store-purchased titles so they happened to be picked up if they existed.
For any users who have synced store-purchased titles previously, and have duplicate highlights, they'll need to manually remove them from their Readwise accounts but this is a one time thing.