OK, let's break it down a bit.
First off, there are no leftists in America. I say that as an Englishman who has been on the left of politics most of my life. I have talked with, corresponded with, and read the work of a great many Americans, many of whom describe themselves as liberals, progressives and even leftists. I can assure you from experience that these people are centrists at most. I have yet to meet, correspond with or read the work of a truly leftist American.
Sanders is right of centre (there's nothing in his proposals that Boris Johnson would object to, but much that Sir Keir Starmer would find too right-wing).
Biden/Harris is a hard-right ticket, wholly in favour of unregulated capitalism.
Trump has no ideology of either right to left, but is simply a narcissistic psychopath.
So you don't have to worry about a leftist government in America.
Civic disturbances can be explained by the fact that there are no police in America, just a paramilitary force charged with law enforcement and the protection of property (NOT people). Their reaction to peaceful protest - a First Amendment right - is typically heavy-handed and provocative. This causes panic, to which the officers react in the only way they know how - shoot anything that moves and/or is Black.
Another contributory factor can be the arrival of several pick-up trucks full of brain-dead yokels, sloshed to the gills on moonshine, and armed with everything from baseball bats to assault rifles. Faced with this bunch of madmen, your gallant 'police' shit bricks and leave them to rampage.
Finally, those perfect exemplars of capitalist ideology - professional criminals - take advantage of the chaos to steal anything that isn't nailed down.
Billions in damage? I doubt that, I really do. All covered by insurance, anyway.
Yes, people are fed up. Fed up of an incompetent President and an impotent government. Fed up of corporate greed and living from hand to mouth. Fed up of being left to die of a lethal virus while those charged to protect their lives and welfare do nothing.
I don't pretend to know what will happen in November. I do know that if America is to survive, Trump must be removed from office, by any and all means necessary. Including shooting the bastard and all his cronies if that's what it takes.