thats very interesting. The difference seems to be in initial reactions of the police to peaceful protests. With lockdown protesters, police showed up in soft clothes and didn't initiate violence on the protestors.
Regarding the much more serious issue of police brutality, police responded very violently to the initially peaceful protests. They were the ones that escalated things. Very interesting overall, and I think the obvious answer is that left wing causes seem to offer critiques that are much more incisive and dangerous to the government.
Why the "government"? I don't think the police automatically defend the interests of the currently-elected politicians. In the absence of distinguishing evidence, I assign much higher priors to them defending their own interests.