I have a similar issue with bluetooth on the Kickr. If I switch between Ant+ and BT, for the same cadence, BT gives WAY lower resistance and therefore wattage. It’s like BT doesn’t send the same resistance to the Kickr for some reason.
It’s really frustrating, because BT is definitely more stable. I basically switch everything in my house off and I still get drop outs with ANT+, but if I run BT I am spinning out in my top gear on the flats.