I had to search, and I did find a few articles talking about a rumor.
I don’t think the two events are of same scope and magnitude. The Khelif’s case has been a worldwide media case, what I found for was very US-specific and limited to some niche deranged corner of the internet (www.snopes.com/…/katie-ledecky-trans-rumors/ listed Facebook and Twitter posts from individuals and 2 articles).
Possibly I shouldn’t have used US athletes as example. Given how the topic is so controversial there, I am quite sure you can find a few idiots who would make this claim about any athlete.