Thanks for your responses guys.
@deva: Yes, it was always Provia with manual Whitebalance and the same brightness level (+3 is the best I think, since +4 and especially +5 shows really strong clipping in the highlights)
@Alan7140: Yes, this reduced the visibility of the color inaccuracy a bit, but it now also doesn't show any Whitebalance anymore and tbh who wants to shoot Fuji without the film simulations I will try to get my hands on some other X-T2 to see if this is general issue. Maybe its something Fuji can fix via a Firmware update.