Bug or Feature

I do not understand the Calendar overview
I do the workout 1 time/Day and it counts:
83 Max streak
83 curr streak
but 31 total for the läßt 30 days
What does the läßt sum mean.
I do the workout 1 time/Day and it counts:
83 Max streak
83 curr streak
but 31 total for the läßt 30 days
What does the läßt sum mean.