The S21 NEVER had such a sensor but Health ALWAYS would link to and pick up the data from a compatible heart rate sensor, such as the Polar H10 I'm using, and Samsung even provided a list of compatible sensors for use with the app and the Polar sensor is one of them and there is still a button to show Heart Rate on the home screen. Until a recent update killed that process Health would report the H10 data whenever I worked out. I could send you a screenshot showing the collected heart rate data in Health from the last few months before this ability was removed (and WHY would such a critical item be removed intentionally?)
If you continue to experience concerns between the device and Samsung Health, we recommend reaching out to Samsung Health directly by calling 1-855-795-0509.
