“Unsynced data” could mean two things uploading or downloading. I presume you refer to uploading changes to the cloud.
Bitwarden does not have the ability to make changes while offline that would need to be sync’ed later (there is a FR for it, though – go vote for it). When a change is made and the save button is clicked, it immediately uploads the changes to the cloud. “Item Saved” is supposed to be the indication that this all happened correctly. If you are finding that something is not in a freshly logged into web vault (https://vault.bitwarden.com) after having been reported as “Item Saved”, that should become the topic of a bug report (click the green new issue button). As such, “unsynced local items” is not even a concept.
The “last sync” time is when changes were downloaded to your client. As @dwbit indicates, they are adjusting these timers to fix bugs and make it unnecessary for the sync button to be front-and-center.
That said, @bigbill does have a good thought. Perhaps the clients ought to display a warning message “working offline” that includes a “sync now” button if the client has not synced in the past N-minutes.