This may come as a surprise to you, but people often deliberately mislabel themselves for credibility, or believe themselves to be something that they are not. For example, so called ‘leftists’ in the US are actually centrists and by international standards.
You are holding all women feminists accountable for the actions of a few self-proclaimed women feminists. That is not infantilization, that is pointing out the impossible standards that women are held to by anti-feminists and how some women will always be blamed for the actions of others.
Lemmy’s userbase is problematic because often times people don’t think about whether or not their experiences are relevant before speaking. Judging by your condemnation of feminists because of misandrists who claim to be one, you don’t seem to understand that feminism is fundamentally about equality and bringing men and women up to par with each other. This goes beyond just women’s rights. Feminism is just as much about making safe spaces for discussions about men’s mental health, male sexual assault victims, paternity leave, custody, and so much more. The reason why these things are not accessible to lots of men is the same reason why women aren’t being treated as people. It’s because of systemic patriarchal barriers that force men and women alike to conform to certain detrimental behaviors or be ostracized.