Decent article summarizing the physiology of hormone replacement, and the resulting impact on sport:
Transwoman Elite Athletes: Their Extra Percentage Relative to Female Physiology - PMC (nih.gov)
From the conclusion:
"Testosterone drives much of the enhanced athletic performance of males through in utero, early life, and adult exposure. Many anatomical sex differences driven by testosterone are not reversible. Hemoglobin levels and muscle mass are sensitive to adult life testosterone levels, with hemoglobin being the most responsive. Studies in transgender women, and androgen-deprivation treated cancer patients, show muscle mass is retained for many months, even years, and that co-comittant exercise mitigates muscle loss. Given that sports are currently segregated into male and female divisions because of superior male athletic performance, and that estrogen therapy will not reverse most athletic performance parameters, it follows that
transgender women will enter the female division with an inherent advantage because of their prior male physiology. "