Copter suddenly "spin" during the flight

Hi community,
The title is not exactly right here, first I know why the copter spin, because one motor is unbalenced during the flight, but when I look the ATT.DesYaw, It’s spining too, I don’t understand it. Is FC try to save the copter, try to make the copter stay in the air?
I have two log about this, One of them are quite big, nothing different between those two log, except this