I think it's because straight white dudes are most likely to be caught up in extreme politics on the left or right online. Feel like a lot of young leftist men went down the right wing pipeline first and then awakened - you've got that political sense activated and use it to backlash on the ideology that you now find so abhorrent.

Also I think they're most likely to be secular where I'm from, whereas other ethnicities seem more likely to have some sort of religious community to find a place that they belong, or they naturally fit into a community of people of a similar cultural background. (In my city the population is very diverse, so these groups are easy to find)

On the other hand white dudes don't have that same sort of culture or tradition, so they end up having to create and find their own form of culture, especially if theyre secular.

In anti-police protests I've seen, a decent amount of the black bloc-ers appeared to be women, seen many a woman waving an anarcho-communist flag or the hammer and sickle, at least where I've been young women seem more politically active in general, and I tend to be in more left areas so I've seen plenty of true left women.