The history of trans participation in Olympic Sports is here ..
https://en.wikipedia.org/wiki/Transgender_people_in_sports#Notable_trans_athletes.
'Since the mid-twentieth century, sports institutions have responded to the participation of transgender women and women suspected to be transgender, male, or intersex by adding eligibility requirements to women's sports variously determined by physical examination, sex chromosomes, and sex hormones.[18] Proponents of such regulations regard them as necessary to ensure fair competition and women's safety.[16][17][19]' TLDR: Men not permitted in the female category..
In 2003, a committee convened by the International Olympic Committee (IOC) Medical Commission drew up new guidelines for participating athletes who had undergone gender reassignment. The report listed three conditions for participation. First, athletes must have undergone sex reassignment surgery, including changes in the external genitalia and gonadectomy. Second, athletes must show legal recognition of their gender. Third, athletes must have undergone hormone therapy for an appropriate time before participation, with two years being the suggested time.[30]
It was not until 2004 that the IOC allowed transgender athletes to participate in the Olympic Games.[. TLDR: 2003 - 5 Olympic Games ago, surgery, legal recognition and hormone therapy required
'In 2015, the IOC modified these guidelines ......require only that trans woman athletes declare their gender and not change that assertion for four years, as well as demonstrate a testosterone level of less than 10 nanomoles per liter for at least one year prior to competition and throughout the period of eligibility. .... These guidelines were in effect for the 2016 Rio Olympics, although no openly transgender athletes competed. TLDR: 2015 Testosterone suppression required.
2021 was the controversial games of Laura Hubbard. Two non binary athletes, female sex, also competed. TLDR: 2021 - This is the first time that openly trans athletes have competed in the Olympics.
In November 2021 the IOC issued a non-legally binding framework that focuses on ten principles of inclusion: "prevention of harm, non-discrimination, fairness, no presumption of advantage, evidence-based approach, primacy of health and bodily autonomy, stakeholder-centered approach, right to privacy and periodic reviews". TLDR This framework is more open to the idea of trans participation in opposite sex competition but passes responsibility to the individual sporting bodies to determine what is defined as an 'unfair advantage'.
Starting from 31 March 2023 all male-to-female transgender athletes who have been through male puberty were excluded from female World Rankings competitions. World Athletics created these rules as a way to ensure fair competition in the women's category. TLDR: World Athletics responded with the answer that the line is drawn at male puberty.
All eyes on 2024!!