Any online form of racing/competing with have people taking advantage of it......to just straight up cheating.
I'm 'competing' (very loose sense of the word) in the Ironman Virtual series. Every weekend they set a distance target for 2 runs and a ride (as we obviously can't swim at the moment). The runs are no problem, as people have to go outside to do those (or even on a treadmill it's reasonably realistic in terms of speed/effort).
The rides though......jesus! I try not to look each week, but I can't help it. When you see people barely able to run a sub 90 half marathon, putting in world record 90k times etc.....you have to laugh. Most put their rides openly on Strava too, so you can see the complete ridiculousness of someone riding at 30+mph at <100W. One guy, for the 20k ride, started at the top of the Alpe de Zwift then blasted down it! I mean come on!!