Peng Shuai made a recorded announcement that she never accused a high official of some sexual crime. We know this is false — people saw her statement. She did accuse him.

For a ruling organization that has contempt for truth, such as the Chinese Communist Party or the Republican Party, it is perfectly acceptable to flat-out deny what people know. In China, hardly anyone dares contradict an official lie. Republicans have convinced tens of millions of cultists to believe lies willingly when they come from the cult's leaders. Partly because they expect to be drummed out of the cult if they ever disagree.

I don't see any description of what Peng said the official did, other than "sexual assault", which is not specific. It covers a wide range, so we don't know what kind of act she is talking about. However, in this case I expect it had to be rather grave, to motivate her to take such a risk.