Having trouble sprinting this year

Been using Zwift since 2017. I’ve got the Tacx Neo smart trainer. Erg mode on 100% difficulty (also tried 0%, no difference in sprints).

For some reason I am unable to get proper wattage while doing high speed (40+kmh) sprints, 400-500W tops. It feels as if I am riding downhill and the trainer won’t give me proper resistance. Has something changed and can I fix this? I am in major disadvantage in races.

Low speed sprints and uphill sections still work properly, I can reach 1000W+ no probs.