Heart rate data and floor data are incorrect

My APPLE watch s2 has never had such a problem, not even HUAWEI bracelet s7, even though it only costs $20。Did I pay $1,000 for a piece of junk?

I found that the vertical velocity kept reading during the motion，

• Why is the floor zero

As for the floors counting, have a look at this thread: What's the secret to tracking stairs accurately?

Regarding the HR, there is an official document at: The Heart Rate Sensor on My Garmin Watch Is Not Accurate | Garmin Customer Support 

Thank you for your information, but why does the app still only use altimeter and barometer to calculate altitude when the watch clearly has gyroscope and accelerometer?

1736310 said:

but why does the app still only use altimeter and barometer to calculate altitude when the watch clearly has gyroscope and accelerometer?

The combination of all of them is used. The change of altitude detected by the altimeter is not sufficient alone. It must be supported by the accelerometer data detecting the steps too. That helps excluding situations when you change the altitude without walking - for example taking an elevator, riding a car, etc.

Did you try calibrating your ABC?