Last spring, I was riding the Leith Hill KOM at a steady 220 watts and all of the sudden realized that my avatar was sprinting past everyone and I was seeing 2000 watts on the screen. I stopped pedaling and tried to unpair/re-pair the power meter but it kept doing it. I also tried to re-calibrate it through the stages app and that's when I realized the battery was super low. Replacing the battery in the PM returned everything back to normal.
While I was troubleshooting, some dork started calling me out in the game chat for "cheating". It wasn't like I was blasting along at 2000 watts for several minutes. I probably noticed within 10-15 seconds, stopped and tried to sort it out, and then re-tried a few times (resulting in maybe 5-10 more seconds of 2000+ watt riding) before giving up and ending my ride. When I exited, I got a notification that Zwift had flagged the ride and wouldn't include it in my stats.