This is an artefact of Strongbox synchronisation code. Synchronisation code does not mean or have anything to do with a remote or network copy. Rather it is the reconciliation process that occurs between Strongbox's temporary working copy of your database and the destination or final copy of the database. This process involves checking the original database, technically termed "remote", for any changes that may have occurred since Strongbox unlocked your database, and if there are any, managing a merge process, otherwise simply overwriting it.
'Remote' is a technical term and is used, even for Local Device databases internally. This is because the Sync process is separate from, and agnostic to the location of the database. So, even if your database is stored on the local device, it is still technically termed 'remote' by Strongbox's sync process.
So, in short, no network activity or remote cloud activity is occurring, this is just a technical term of art we use internally which can cause confusion.