In one study, female detransitioners were three times more likely to be lesbians than to be straight.
A study  of 100 detransitioners, the majority of whom were female, showed that 26.1% of the females were homosexual before they transitioned.
Only 8.7% considered themselves heterosexual.
 Littman, L. (2021). Individuals Treated for Gender Dysphoria with Medical and/or Surgical Transition Who Subsequently Detransitioned: A Survey of 100 Detransitioners. Arch Sex Behav. [Link]