On Android 8 to 13:
Go to the Home + Security app > Settings > Notifications, to access advanced notification settings.
Notifications are classified into "channels" for each kind of events (unknown faces, Indoor/Outdoor Camera motion detection, Smoke Alarm...) and you can choose the behavior for each channel.
You can disable notifications for certain channels or even change the sound for a specific channel if your Android phone allows this option.
On Android 14:
An option must be activated in your phone's system settings before you can follow the above instructions.
Go to your phone's settings, select “Notifications” then “Advanced settings” and activate the option “Manage notification categories for each application”.
Once this option has been activated, you can follow the instructions for Android 8 to 13.
Updated