Turn off all the notifications categories except the ones you actually want notifications for. You have to do this in the phone's notification settings. Any notification you turn off will not appear on your watch. The category you are showing that notification for may be "coaching and insights", not marketing. When get that notification on the watch, you can also hit the "turn off notifications from Samsung Health". This, to my recollection, will only turn off that particular notification only, and only if it's coming from the companion app on the watch.
