It's been gone for awhile. The carbon driveshaft was replaced with a steel driveshaft back in 2017. I don't anticipate it being offered for the G generation M3/M4. I think it may be linked to the fact that BMW had a recall on the carbon driveshaft eight months prior.
See link:
https://static.nhtsa.gov/odi/rcl/201...8V713-2564.pdf