Reality.

As measured two ways. First, it is always way high against my Wahoo Kickr. So I compared it to other Wahoo Kickrs, and it's also very high compared to them. Also, when I look at my segment times on Strava against others with similar times, I'm always showing way higher average power then everyone else (and I'm not an outsized person).

I have no doubt it reads very, very high.