The police are often between a rock and a hard place during these demonstrations - from whatever political standpoint. If they come down too hard, they can sometimes escalate the situation and face accusations of brutality; but if they stand back and leave things to develop, this often reduces the violence, but leaves them open to accusations of condoning the cause or allowing too much leeway, e.g. the Colston statue demonstration (which I think they got right).
The police are often seen as the enemy when they are trying to control a demonstration, and it does not matter what the political affiliation of the marchers is.