Hi Bastian, I had a similar issue.
In my case, both flaps were trimmed up by about 5mm after a flight with SERVO_AUTO_TRIM enabled.
I had the impression that the ailerons were trimmed correctly and moved both flaps back down by exactly the same amount with SERVOx_TRIM so that I wouldn’t change the roll moment again.
Unfortunately I was not able to find the corresponding code. But I found this thread: SERVO_AUTO_TRIM both ailerons up
Maybe we can ask @iampete to take a look at the logs.
I’m running at the moment V4.1 Beta5 too.