It may be doping.
However, a friend of mine who was deeply involved in hot rod/car racing at national championships told me something that surprised me. He said “We could have set the record any time we wanted to be we didn’t because we wanted to save some back for the championships.” In other words, they were sandbagging. I wonder if some of that isn’t going on here?
Sandbagging or eye on the prize. Holding records is nice, but you’re still in competition to win. I don’t think we ever really found out how fast Usain Bolt could go. He just went out and won, and yeah set the record a couple of times, but that always seemed to be more about him having to go that fast to win. He never seemed like he was really pushing to his outside capability.