Contradictory lab values of LH/FSH vs Testosteron in preOp/postOp?

Many transfem friends have values nuked to consistently to 0-10 ng/mL free Testosteron with much lower dosages than me.

I've been taking a big dose of Antiandrogens for 2 years (cyproteronacetat) and still have a not completely negligible value of free Testosterone in my blood. 0.51ng/L (sometimes it oscillates a bit higher)

However the hormones that signalized testosterone production to the testicles are more than well down-regulated (FSH & LH)

Where are those 51ng/mL Testosterone being produced if not in the testicles? (As the production there should be stopped given that both FSH and LH values are below 0.1 ug/L)

I am worried what to do with those high values as surgically castrated AMAB people are below 20ng/mL Testosterone, but even after my GaOP I guess I will probably stay >50ng/dL T.

Do you have similar experiennces? Will that go away after my GaOP? if not how can I control that T production postOP??