In HTC phones running
Android 7, all app icons can display an icon badge showing the number of unread or pending notifications.
From
Android 8, only HTC app icons can display the number of unread or pending notifications on the icon badge. Other apps will show a dot—called the notification dot—to indicate there are notifications that you've not seen or acted upon.
Note: HTC app icons can show both the icon badge and the notification dot.