I have enabled “last notification” to monitor Deliveroo (food delivery service) status.
It is correct when there is only one notification.
When there are more than one notification, i.e., unread notification got grouped, the HA sensor does not work. It shows the app name instead of the notification content.
That is how sms works too, not exactly the same but it doesn’t look the same as with just one notification.
I believe this is part of Android.
At least it’s because of Android it works that way with sms.