What are they protesting against when Forrest sees Jenny again?

When Forrest sees Jenny again, she is protesting against the Vietnam War and the societal issues of the time, including civil rights and anti-establishment sentiments. She is involved in a rally, expressing her discontent with the government's actions and advocating for peace and change. This moment highlights the contrast between Forrest's straightforward nature and Jenny's tumultuous journey through the counterculture movements of the 1960s and 1970s.