These may just be your basal calories. According to What is the difference in "active cal… - Apple Community
Total calories include - basal calories + calories burned when doing a workout. Active calories are those that are burned during some activity like swimming running or anything else where your body is moving, Basal are those that your body burns during a day without any activity.
To see the total calories burned for the day first, tap on the Activity app (and History at the bottom left corner if not already selected - then select a day). Then swipe left in the "Move" section to not show the graph and show the Active and Total calories. (Swipe right to return to the graph.). Or, you can use the Health app - tap on Activity.
The first (and simplest) thing to try if you believe something isn’t working right is to restart your Apple Watch and its paired iPhone. If necessary (device not responding), try a forced restart. Both methods can be found here:
How to restart your Apple Watch - Apple Support
Restart your iPhone - Apple Support
If that doesn't help, the next steps would be to unpair and pair your watch again and restore from the backup just created. This should result in no loss of data. It deletes all temp and corrupted files and re-indexes the file system.
Unpair and erase your Apple Watch - Apple Support
Set up your Apple Watch - Apple Support