Matt’s probably right. That’s the way that many Rotax users utilize to get a feel for their jetting.
Your clutch is not disengaging at high revs when you release the throttle. Your RAVE should have nothing to do with that, too. It doesn’t matter if your carb was “tuned,” you still need to match the air quality of the moment. Under the same air conditions, if you went up one jet size, the issue would most likely be gone.