Sudden (and repeated) cut of throttle power in VTOL mission

Hello everybody,

I am experiencing an unusual behavior of my VTOL during a mission (which I have flown repeatedly with the similar result).
During a mission, while loitering around a point, the aircraft suddenly cuts power of the propulsion motor, looses speed and goes into transition after having reached the minimum speed limit. As such, the failsafe is working properly, however, I can not identify the reason for the throttle cut, as the mission plan does not indicate anything like that.
To be precise, the issue occurs during WP20, which is 3 turns of loiter, after about 2.5 turns, before continuing to WP21 and WP22 (landing). I re-flew the same mission multiple times and experienced the same behavior each time at practically the same point, so one might think that it should be related to the mission plan, but I can’t find any problem with.
Might it be a parameter value that results in this?

I add the mission plan (and the bin log file in the google drive) of the last flight, where the issue is starting @11:29:32:012 with a cut of the throttle of the main motor.
2023-05-15 11-22-06.bin.param (24.4 KB)
2023-05-12-2.waypoints.txt (2.1 KB)
VTOL bin log

I hope that somebody can point me to the right direction regarding that issue…

Thanks in advance,