Samsung Health is going to stop syncing with third-party apps, on September 1. Samsung is currently notifying Samsung Health users to let them know that the third-party apps will stop syncing on September 1. All third-party apps will be removed from the service, except for Strava. Samsung is also removing the UV Tracker, Temperature and Humidity (TH) tracker as well, from Samsung Health. Samsung does say that users can still back up that data and export if, to take to another service, however, which is pretty nice of Samsung there.
The move to remove third-party apps from Samsung Health has not been explained by Samsung (and likely won't be). But it does mean that the health app is going to be less open then it was - and less open than its competitors. Samsung Health has been one of the more robust health and fitness apps out there, particularly since the rebranding from S Health to Samsung Health. It can track virtually everything, and that data was able to be taken to other services, or use other services to bring it into Samsung Health. With the app, you can track your calories burned, steps taken, your workouts and much more. But it also has an auto-fill feature for tracking calories during the day. Something that many other health and fitness apps still do not feature.
Those that use Samsung Health to sync their data with other services like Fitbit, Microsoft Health, Runkeeper and others, you may want to look at another alternative than using Samsung's Health app here, as you'll no longer be able to sync that data. With Fitbit having just announced the Charge 3, it may be a good time to pick one up and invest in Fitbit's ecosystem - which does allow syncing to these apps and many, many more. Remember to download your data before September 1 (this coming Saturday).