Anecdotal only - when I was in university (20 years ago) a lot of the student protest stuff was coming from the student equivalent of professional politicians. They were undergrad mostly (a few grad students) but usually had been in university for like 8 years and were ideologically motivated to stick around pursuing political aims, rather than just be there to advocate for their fellow students.
I was marginally involved in student government, and there was a big difference between the (majority) that were there to make sure their faculty/department got representation, and those that were trying to co-opt student government for some broader political aim. Unfortunately, there is rarely enough of an opposing force on these people, and inevitably they have an outsized influence.
So I wouldn't really think of it as undergrads as a whole, more like some 30 years old taking 1/4 course load and pushing their politics.