So trans men on hormones would be more sensitive to anesthesia and trans women on HRT would be less sensitive to anesthesia. Also cis women with PCOS would be more susceptible to anesthesia.

Trans men on testosterone, yes; cis women with PCOS, yes (provided their testosterone level isn't reduced through treatment); trans women on HRT - maybe.

It's about levels of testosterone, so any woman (trans or otherwise) with high levels of testosterone would be more sensitive. If a trans woman on HRT (estrogen) still had a relatively high level of testosterone then she would still be sensitive to anesthetic.

It's not really got anything to do with levels of estrogen. In fact, it mentions that removal of female sex organs (oophorectomy) has no effect. However, it does mention "Conversion of testosterone to estradiol [a form of estrogen] by aromatase is partially responsible for this effect." which, I'll be honest, is beyond my understanding of how hormones work in the body (gonna have to dig in and read the cited sources). It does not seem that estrogen pathways have this effect, rather it's testosterone in its normal, uninhibited biochemical pathways that does it - inhibiting aromatase lowers sensitivity, in spite of higher testosterone levels.