Same with mine. I barely did exercise yesterday, but it shows I burned 6,727 calorioes. Then today in only an hour of being awake I already burned almost 2k calories. Definitely not right and it's driving me insane as this is a feature I look at often. Wish there was a fix for it!
I've got two issues with mine:
First, It doesnt keep the record of entered data for my intake calories while it's synced with samsung health installed on my V20. Usually it resets to zero in middle of day or goes twice over what was entered and shows non sense numbers. I disabled the health program on my phone and it seems to be working ok on the watch.
Second issue is calorie counter on workouts and heart sensor that stop measuring every day and I have to restart the watch to get these back to working.