Is it? Could data sampling rate differences be having an effect? If the fast Race Mode option is enabled in Wahoo but you’re not connecting to Zwift app via wifi or DirectConnect, would the bike record natively at high sampling rate but Zwift still receiving at lower rate? Depending on which data packets made it to Zwift, it would be working with a different and incomplete set of data than Wahoo, right? Particularly when effort level is quickly variable, like a brief surge up a roller, there’s more opportunity for discrepancy between data sets. I dunno…but Race Mode is supposed to improve responsiveness in Zwift by minimizing data gaps from the trainer’s PM.

Even outside of Race Mode, wouldn’t a slow ANT+ connection to Zwift show data packet variance compared to the Wahoo recording (via Bluetooth to the phone)?

Wahoo also has the power smoothing feature for ERG mode, which if you have that on, may also be a factor.