Short power drop issue

[Failons]

Hi everyone,

My beloved Z4 E89 23i had a strange behavior in the last months, and I wanted to know if all your engines are doing the same, and I’ve just missed to notice it before.
It has a short power drop just after you push the throttle, every time, for a second, just like it’s struggling a bit, then comes up beautifully again; this happens ONLY in normal driving mode, nothing in SPORT.
Mechanic can’t figure out what it might be with a brief conversation.

Any similar behavior noticed on yours, or knowledge about what feature that might be?

Many thanks in advance


Marco