Relevant section:
'Applications from trans women and non-binary people assigned male at birth, aged 16 and over, who intend to compete in the Women’s category will be considered by an Expert Panel established by British Rowing, consisting of medical experts and a legal representative.
Domestic Competition: The eligibility requirements for trans women or non-binary competitors assigned male at birth to compete in the women’s category, and who are not intending to represent their home country or compete internationally (i.e. trial or join a British Rowing funded performance programme), will require: a blood hormone test to demonstrate hormone levels of less than 5nmol/l; confirmation their treatment commenced at least 12 months prior to application; and, commitment to test results and such other medical information as the Expert Panel may request. They may be subject to spot checks.
Alternatively, they may be able to confirm and provide evidence satisfactory to the Expert Panel that they have undergone gender reassignment surgery and are not producing testosterone.
Performance Pathway / International Competition: For trans women or non-binary competitors assigned male at birth who intend to compete in the women’s category, and represent their home country or compete internationally (i.e. trial or join a British Rowing funded performance programme) the eligibility requirements are those of World Rowing’s eligibility requirements as set out in World Rowing’s Bye-Laws concerning eligibility by gender for men’s and women’s events.'
It's been extensively shown that testosterone levels alone are far from the only advantage that males have over females. If you've gone through male puberty, there will be many other aspects that give you advantages over females - bones, muscle, lung capacity etc.