Does the notification content disappear after the month ends??!! (Revised)

I bought Shinsegae gift certificates in preparation for the Great Festa and received a notification that they were issued. But when I tried to find the notification to redeem them... it only shows notifications from October 1stㅠㅠ They arrived around September 29th or 30th... ---------------- Checked and confirmed: Notifications before October - visible on my secondary phone for gaming. Not visible on my primary phone (calls, messenger)..... wow