The heart rate sometimes changes its color and shows a number next to it. Here’s the explanation about what that means.
That’s the heart rate zone you are currently in, it’s none or a value between 1 (low) and 5 (high)
The color also reflects the heart rate zone (Default or Grey, Blue, Green, Orange, Red)
If you don’t like the colors and/or numbers, I allow to disable them inside the customisation field.
If you want to show the customisation field documentation, select you watchface below and click the link that shows up afterwards.