Xiaomi
Hide Notifications for Hidden Apps auf Xiaomi
Hiding an app with App lock on Xiaomi only masks its icon in the app drawer. Notifications keep arriving as usual unless you turn off previews separately, so a locked messaging or banking app can still flash a full message on your lock screen.
MIUI splits app hiding and notification hiding into two settings on purpose. This lets you keep receiving alerts for a sensitive app while still hiding its icon, or the opposite: hide the notification content but leave the icon visible.
To stop notification previews for a hidden app, open Settings ➔ Apps ➔ App lock ➔ Settings and enable Don't show notifications. Once active, the system withholds message content until you open the app and unlock it with your PIN, pattern, or fingerprint.
Disable the same toggle if you want previews back, for example when you rely on notification badges for a work app you no longer need hidden. This setting applies per app added to App lock, not globally, so check each locked app individually if several of them still show content.