Why is the [Dismiss] option on the Xiaomi Smart Band 9 only available for some notifications?

The Xiaomi Smart Band 9 supports notification aggregation. The APP type is related to whether the notifications are aggregated or not. You can't delete the notifications that are aggregated or in the aggregated notifications. Tap the aggregated notification card to enter the aggregated notification list, and the [Clear all] option will be displayed at the bottom. You can tap [Clear all] to clear these aggregated notifications.