This sounds like a urban legend or an isolated incident portrayed to make the issue sound big and scary.

Prisons should be evaluating whether the person was genuinely living as a woman (and possibly taking hormone treatments, etc) before putting them into a women’s prison, and not just because they declared “I’m a woman now” after being convicted and sentenced.

Nobody making a fuss about trans people causing problems in prisons seems to give a single fuck about all the sexual assaults and rapes that happen between men or between women in prisons. It’s only when trans people come into the picture then all of a sudden prison rape becomes a big issue.