This is the dirty tricks that the uneducated play sucker to:

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1. The "violence" in left-wing protests is typical limited to a few broken windows

As you note, most likely by right-wingers or apolitical sh*t-stirrers and self-interested looters. Organizers always instruct everyone to be peaceful and careful to avoid damaging anything.

Right-winger protests? J6 resulted in what, 1500+ people convicted of crimes, many including violence and destruction and theft. By far the most violent and lawless protests in ages, and of course it was right wing.

At left wing protests, most of the violence is by right-wing counter-protesters and police doing things like pepper-spraying people sitting on sidewalks not hurting anyone.