Interesting. Back in May there were some instances during the Giro TT challenge. The one where I got a screen shot had the rider going up a 5% grade in Watopia at 175 km/h at 188 watts. And appeared to be 13th on the live leader board in the Giro TT in Bologna at the same time.
Maybe this is some event/world glitch that produces an absurd speed result simultaneously for one Zwifter in one Zwift world and normal results in the other.