From the abstract:

How do protest actions impact public support for social movements? Here we test the claim that extreme protest actions—protest behaviors perceived to be harmful to others, highly disruptive, or both— typically reduce support for social movements. (...) participants indicated less support for social movements that used more extreme protest actions. (...) Negative reactions to extreme protest actions also led participants to support the movement’s central cause less, and these effects were largely independent of individuals’ prior ideology or views on the issue

Taken together with prior research showing that extreme protest actions can be effective for applying pressure to institutions these findings suggest an activist’s dilemma