Nothing has changed about that entry in the fitness tracker. If it's dramatically different, you might want to double-check your most recent weigh-in to make sure it's correct, since the calories burned is based on that information.
I do Zumba. I track it under "hip hop, zumba.....". It has always bee 600 calories burned. Today is it 270 calories burned. I know I lost a few pounds, but I don't think that caused the problem. Is this a result of your outage?