It's a difficult question, because obviously violence is out of line for protests about many topics, while just as obviously necessary for some.

I think think that violence or vandalism in this case was unwarranted, but there are some other in this thread who believe otherwise.

I guess that I'd say that, probably, vandals/criminals should always be punished, because they're doing clearly illegal things... and it's up to the protestors to judge whether the cause they're supporting is really worth going to jail for. If sufficient numbers of people feel that, you have a revolution.

(And also, a separate issue, whether the violence is actually going to benefit their cause. It probably won't.)

I certainly don't think that we should be in a position where courts are are judging certain crimes as forgivable because of their cause, while supporters of other causes get the full weight of the law for similar actions. I think the vandals on Jan 6th should get the same punishment as, for instance, similar vandals during BLM.