I noticed that my kcal burned for activity level changes daily even when my kcal burned for BMR stayed the same. Shouldn't it be a fixed percentage of my BMR? Or is it somehow impacted when I record exercise for that day?
I think the calculation is that if you log your exercise, you are not in the "activity level" mode to avoid double counting. The more time you spent exercising, the lower the energy you should see under "activity". If you don't (log) exercise at all you should see your "activity" expenditure to be what is determined on your profile.