I am slower after switching from Kinetic Smart 2 to Control Bike Trainer

I have been using the inride-based kinetic road machine smart 2 for a couple years. I recently upgraded to the T-6400 with smart controller. My power output goes down by between 10-20% in zwift races. I have tried doing the exact same race and the gap is pretty constant. Anyone else having this issue? Which is the most reliable one? Thanks!