QuadPlane Loiter_to_altitude mode abnormal behaviour

Hello, we have tried the loiter_to_altitude waypoint to ascend and descend to and from 200m height. The both parts worked well and mission was flown succesfully. but on the descend from 200m vtol did a strange thing, although it had reached its targeted altitude, it again did a one more loiter around the waypoint and ascended to higher altitude. the ascending part was not supposed to happen?I am asking for is it normal? Why it might happen? Is there something behind going on that I am not aware of?

00000037.BIN - Google Drive here is the log