As an Autistic trans man of his own genders (I am also multigender and nonbinary, plus agender), periods suck and remind me that I wasn't born as a man I wanted to be (also reminds me of how people perceive periods in a gendered way as). Periods also strengthen the emotionally and mentally fragile states I am in (plus intrusive thoughts, internalised bigotries and transphobia, including personal issues), and the self-misgendering plus self-deadnaming increases during them.
I also hate the ickiness I feel (especially since my periods and hormones are fucked because of my hereditary hypothyroidism).