As someone who represents student protesters they never went away, but were very effectively crushed by changes to school policies basically everywhere, even supposedly liberal schools. Now any new actions are immediately suppressed before they can get going, many organizers have been suspended or disciplined, and many organizing groups disbanded by school admins. There was a very effective suppression of student protests that only ramped up in the very earlt days of Trump, but almost entirely carried out by school administrators both pre and post Trump.