if I leave my watch in an ‘Open Workout’ during the day it says I burn over 2000 calories!

The other day I left my apple watch in an open workout for most of my day (about 8 hrs) and by the end I had burnt almost 2000 active calories! It was just a normal day for me, barely any exercise at all! Normally, I will burn about 450 active calories a day without putting my watch in ‘workout mode’. Should I trust the apple watch workout app? When you say you are doing a workout, the watch is measuring your heart beat the whole time so you would think its more accurate? Please let me know if the same thing happened to you and I want to know your thoughts.

I cant find anything on google when I try find info.