Is it the Neo 2 or Neo 2T? I don’t know about the Neo 2, but a lot of people experience the 2T reading notably lower than their pedals (myself included). I just don’t bother with power from the trainer. I use Power Match indoors, and outdoors is obviously just the pedals, so it’s the same measuring device anywhere I ride. As GCN found out recently, 200W into the pedals is 200W into the pedals.
I don’t know which Tacx trainer this person used, but they saw similar numbers to you.