Men cannot call themselves Feminists. They can write things that are Feminist, say things that are Feminist, do things that are Feminist, but for all intents and purposes, men can only be Feminist allies - and even then I’m a bit iffy about men who self-designate themselves as such. If anything, men can only claim to be better men.
Instead of shouting about how Feminist you are despite being a man, it’s far more effective to shout about actual Feminist ideas and seek no special treatment as a man. Just… meet minimum standards of human decency, and not expect to be let into a club formed to combat special treatment of men.
Feminism is a movement for women by women. Men can help by going into spaces that are unsafe for women/typically masculine/patriarchal and call out misogyny and other forms of bigotry, and using their social privilege as leverage to get Feminist ideas to people who wouldn’t normally listen, that’s cool - BUT mansplaining, use of privilege to give weight to their voice, denial of privilege/defense of problematic men, and bewailing “not ALL men are like that!” really means I don’t like calling men (and that includes myself) straight-up Feminists.
Yes, everybody will benefit from a dismantling of patriarchy/kyriarchy and arbitrary gender roles, but an ally and advocate for LGBTQIA+ rights wouldn’t call themselves queer, why should a man call himself a Feminist for any reason other than brownie points and entitlement?