One of Android's useful privacy settings is the ability to set notifications to only display none private content meaning no name or message content on lock screen and notification shade. For example, a WhatsApp message would only show "1 WhatsApp message". And this can be changed for each conversation in each app individually.
Garmin notifications override this for no reason. Regardless of notification display settings, the watch (F5X in my case) will show full message text and name.
Why expose user information. It's actually easier to code to respect "Notification channel" settings than it is to code to ignore them.
This would mean private information would stay private without having to disable the whole notification for the app. Especially important for apps like banking.