Here is a solution from another forum member;
LiftRunRead
Move Ring
RESOLVED: my move ring would unexpectedly lose calories. For example, after exercising, my Apple Move ring would show 500 calories. But later in the day, it would drop to 425. I discovered this was due to a duplicate workout recorded from my connected Strava fitness app, which would record fewer calories. So I deleted my duplicate Strava fitness data from the day’s workout, and my Apple Move calories returned to their original count. Hope that helps.
It seems to do the same thing with other 3rd party apps as well.