A split flywheel is made out of two parts which are vulcanised together. The reason for this is to work as an antiresonance/vibration limiter. It is next to impossible to mill it properly if it is split.
All other flywheels are single piece ones. In the Fiat group it all of a sudden overcomes the engineers to implement such measures whether needed or not. And some months later they might get the idea to reverse it because it is too costly.