I just wanted to confirm that it is actually expected to see this notification after a schedule scan even if there were no detections, but there's been a bug that has kept it from displaying properly in the last couple releases.
We plan to eventually have this notification honor the "Show Malwarebytes notification in the Windows System Tray" setting in Application Settings. That way you can control whether it's displayed or not. But since it auto-dismisses now after a couple seconds hopefully it's not too disruptive. I know other users appreciate seeing this notification occasionally, as they like the confirmation their system is clean.
Thanks for the feedback on the issue!