I have a similar issue. I started using my good bike with a Quarq power meter connected to my Wahoo head unit and checked the power it was displaying against the power showing in Zwift from my Wahoo Snap… I wouldn’t mind if the differences were small %, but this was out by a lot. Zwift was regularly showing 15% more then my power meter. I don’t know which is out… the trainer… zwift or the power meter!