No. There's no automation that deletes or archives rows from your notification history — the nightly cleanup job only prunes the separate admin activity log, not the notification feed. Every notification ever generated stays in the database indefinitely; marking one as read only flips a read/unread flag, it never removes it. In practice this is invisible day to day since both the bell panel and the full notifications page load in pages, but if you're relying on this for long-term reporting, keep in mind the underlying data grows without limit.