Damn I was hoping this issue would be fixed in the PHEV but I guess it's not. Not sure if they still intend to fix it in a future patch. Does it happen in all modes, including EV only?
This is a VSC / traction control "bug" (they claim it's not a bug, but a feature) introduced with the Facelift H6 variants. When VSC detects excessive wheel spin, it kicks in more aggressively to limit power to the wheels.
Pre-FL H6 HEV doesn't have that since the VSC algorithm is more relaxed and lets the wheels spin for longer instead of trying to reign them in. It basically worked as VSC set to off for a few seconds, which technically is dangerous.
It's not an issue with Launch Control because you need to turn off VSC to enable launch control.